CSLB General Building (B) — All Questions

In residential load calculations, what does an ACCA Manual J procedure primarily determine?

• a.The size and gauge of supply ductwork
• b.The heating and cooling loads of a building based on its construction and climate✓
• c.The refrigerant charge required for the condenser
• d.The electrical service size for the panel

Manual J is the industry-standard residential load calculation method. It estimates the sensible and latent heating and cooling loads by accounting for construction, insulation, windows, orientation, infiltration, and local design temperatures. Equipment is then selected to match those calculated loads.California Energy Code (Title 24)

One ton of cooling capacity is equal to how many BTU per hour?

• a.6,000 BTU/hr
• b.9,000 BTU/hr
• c.12,000 BTU/hr✓
• d.15,000 BTU/hr

A ton of refrigeration equals 12,000 BTU/hr, derived from the heat needed to melt one ton of ice in 24 hours. This unit is the standard used to size air-conditioning and heat-pump equipment. A 3-ton system therefore provides about 36,000 BTU/hr of cooling.

A common rule-of-thumb airflow value for a residential cooling system is approximately how many CFM per ton?

• a.100 CFM per ton
• b.400 CFM per ton✓
• c.800 CFM per ton
• d.1,200 CFM per ton

Standard residential cooling airflow is roughly 400 CFM per ton, though it may range from 350 to 450 depending on climate and humidity. A 3-ton system therefore typically moves about 1,200 CFM. Correct airflow is essential for proper capacity and dehumidification.

A 4-ton air-conditioning system is designed at 400 CFM per ton. What total supply airflow is required?

• a.800 CFM
• b.1,200 CFM
• c.1,600 CFM✓
• d.2,000 CFM

Multiply tons by CFM per ton: 4 tons x 400 CFM = 1,600 CFM. Sizing the blower and ductwork for this airflow ensures the coil receives adequate air for rated capacity. Undersized ducts would restrict this airflow and reduce performance.

The sensible heat formula uses which constant when air volume is in CFM and temperature difference is in degrees F?

• a.0.68
• b.1.08✓
• c.4.5
• d.0.24

Sensible heat (BTU/hr) equals 1.08 x CFM x delta-T, where 1.08 combines air density, specific heat, and a time conversion. The 4.5 factor is used with enthalpy for total heat, and 0.68 is used for latent load with grains of moisture. These formulas let technicians verify airflow and capacity.

Using the sensible heat formula, how much sensible heat is removed when 1,200 CFM of air is cooled through a 20 degree F temperature drop?

• a.12,960 BTU/hr
• b.18,000 BTU/hr
• c.25,920 BTU/hr✓
• d.32,400 BTU/hr

Sensible heat = 1.08 x 1,200 CFM x 20 F = 25,920 BTU/hr. This calculation lets a technician confirm the coil is delivering close to its rated capacity. A result far below expected suggests low airflow or an undercharged system.

What does ACCA Manual D provide guidance for?

• a.Selecting the correct condenser
• b.Sizing and designing residential duct systems✓
• c.Calculating building heat loss
• d.Selecting the proper thermostat

Manual D is the ACCA standard for residential duct design. It uses the available static pressure and required airflow to size trunks, branches, and fittings so each room receives its design CFM. Proper duct design prevents noise, high static pressure, and uneven comfort.

After a Manual J load is calculated, which ACCA procedure is used to select the specific equipment model?

• a.Manual D
• b.Manual T
• c.Manual S✓
• d.Manual RS

Manual S matches equipment to the Manual J loads using manufacturer expanded performance data at local design conditions. It ensures the unit meets both sensible and latent loads without gross oversizing. Oversized equipment short-cycles and dehumidifies poorly.

Oversizing a residential air conditioner most commonly leads to which problem?

• a.Higher heating capacity
• b.Short cycling and poor humidity control✓
• c.Lower refrigerant pressures
• d.Reduced supply air temperature

An oversized unit cools the air quickly and satisfies the thermostat before it runs long enough to remove moisture, causing short cycling. The result is a cool but clammy space and increased wear from frequent starts. Correct sizing from Manual J and S avoids this.

Which factor increases a building's cooling load the most on a hot afternoon?

• a.Large west-facing glass with direct solar gain✓
• b.North-facing insulated walls
• c.A well-sealed attic hatch
• d.Low-wattage LED lighting

West-facing windows receive intense direct solar radiation in the afternoon, adding substantial sensible heat gain. This solar load is often a dominant component of the peak cooling load. Shading and low-SHGC glazing reduce this gain.

In California, plans for new HVAC systems typically must demonstrate compliance with which energy standard?

• a.The National Electrical Code
• b.Title 24, Part 6 energy efficiency standards✓
• c.The Uniform Plumbing Code
• d.The Americans with Disabilities Act

Title 24, Part 6 sets California's building energy efficiency standards, including HVAC equipment efficiency, duct sealing, and refrigerant charge verification. New and altered systems generally must show compliance through prescriptive or performance methods. Documentation is submitted with the permit application.California Energy Code (Title 24)

Under the California Mechanical Code, when is a permit generally required for HVAC work?

• a.Only for commercial buildings
• b.Only when replacing a thermostat
• c.When installing, altering, or replacing mechanical equipment such as a furnace or air conditioner✓
• d.Never for residential work

The CMC and local jurisdictions require a mechanical permit for installing, altering, or replacing regulated equipment like furnaces, air conditioners, and ductwork. Permits trigger inspection to verify code-compliant, safe installation. Minor maintenance such as filter changes does not require a permit.2022 California Mechanical Code (CMC)

What is the primary purpose of a Manual J block load versus a room-by-room load?

• a.To size the refrigerant lines
• b.To establish total equipment capacity for the whole structure✓
• c.To determine duct insulation R-value
• d.To calculate the gas meter size

A block (whole-house) load establishes the total heating and cooling capacity the equipment must provide. A room-by-room load then distributes that capacity to size individual ducts and registers. Both are needed for a complete design.

If a home has a calculated cooling load of 30,000 BTU/hr, what nominal equipment size is the closest match?

• a.2 tons
• b.2.5 tons✓
• c.3.5 tons
• d.4 tons

30,000 BTU/hr divided by 12,000 BTU/hr per ton equals 2.5 tons. Manual S guides selecting a unit whose capacity at design conditions closely matches this load. Choosing 2.5 tons avoids the humidity and cycling problems of oversizing.

Friction rate in duct design is typically expressed in which units?

• a.CFM per square foot
• b.BTU per hour
• c.Inches of water column per 100 feet of duct✓
• d.Feet per minute

Friction rate expresses the pressure loss per unit length of duct, in inches of water column per 100 feet. In Manual D, the available static pressure and total effective length set the design friction rate used to size ducts. A higher friction rate yields smaller, higher-velocity ducts.

Air velocity in a duct is calculated by dividing airflow (CFM) by what?

• a.The duct length
• b.The cross-sectional area of the duct in square feet✓
• c.The static pressure
• d.The temperature difference

Velocity in feet per minute equals CFM divided by the duct cross-sectional area in square feet. Excessive velocity causes noise and high friction losses, while too little velocity can reduce throw and mixing. Designers balance velocity against static pressure limits.

A branch duct must deliver 200 CFM at a velocity of about 600 feet per minute. Approximately what free area is required?

• a.0.10 square feet
• b.0.20 square feet
• c.0.33 square feet✓
• d.0.66 square feet

Area equals CFM divided by velocity: 200 / 600 = 0.33 square feet. This corresponds to roughly a 8-inch round duct. Selecting the right size keeps velocity and noise within acceptable limits.

Under California energy standards, duct leakage in many new and altered systems must be verified by which method?

• a.Visual inspection only
• b.A duct leakage (pressurization) test by a certified rater or installer✓
• c.A refrigerant pressure test
• d.A combustion analysis

Title 24 requires duct leakage testing for many new installations and changeouts, typically verified through a pressurization test. Sealing ducts reduces energy waste and improves delivered airflow. Results are often confirmed by a HERS rater.California Energy Code (Title 24)

Which condition would a technician correct by performing an accurate load calculation instead of using a rule of thumb like square footage per ton?

• a.Chronic comfort complaints from an oversized or undersized system✓
• b.A dirty condenser coil
• c.A tripped float switch
• d.A failed run capacitor

Square-foot rules of thumb ignore insulation, glazing, orientation, and infiltration, often producing oversized or undersized equipment and comfort complaints. A Manual J load accounts for these variables and yields correctly sized equipment. This is the proper professional approach.

Latent load in a cooling calculation refers to the energy required to do what?

• a.Raise the dry-bulb temperature of the air
• b.Remove moisture (water vapor) from the air✓
• c.Overcome duct friction
• d.Power the compressor motor

Latent load is the heat associated with condensing water vapor out of the air, lowering humidity. Sensible load changes air temperature, while latent load changes moisture content. Both must be met for comfort, especially in humid climates.

A 3-ton system is selected for a home. At 400 CFM per ton, what is the target blower airflow?

• a.800 CFM
• b.1,000 CFM
• c.1,200 CFM✓
• d.1,500 CFM

3 tons x 400 CFM per ton = 1,200 CFM. The blower and duct system should be configured to deliver this airflow at the system's external static pressure. Verifying actual airflow after installation confirms proper capacity.

What is the main benefit of properly sizing equipment to a load calculation rather than oversizing?

• a.Faster refrigerant charging
• b.Better humidity control, comfort, and energy efficiency✓
• c.Elimination of the need for a permit
• d.Higher supply air velocity

Right-sized equipment runs longer, steadier cycles that dehumidify effectively and hold temperature evenly, improving comfort and efficiency. Oversizing wastes energy through short cycling and leaves the space humid. This aligns with Title 24 efficiency goals.California Energy Code (Title 24)

What is the primary purpose of providing combustion air to a gas-fired furnace?

• a.To cool the electronic controls
• b.To supply oxygen for complete and safe fuel combustion✓
• c.To increase supply air temperature
• d.To reduce refrigerant pressure

A gas furnace needs adequate combustion air so the burner receives enough oxygen for complete combustion. Insufficient air causes incomplete combustion, producing carbon monoxide and sooting. The CMC specifies required openings or ducts based on the appliance input and the confining space.2022 California Mechanical Code (CMC)

When two combustion-air openings are used for an appliance in a confined space communicating with outdoors, they are generally located how?

• a.Both near the floor
• b.Both in the ceiling
• c.One opening near the top and one near the bottom of the space✓
• d.One in an interior wall only

Two openings, one high and one low, allow both makeup combustion air and ventilation of heat. The high opening relieves warm air while the low opening supplies denser cooler air. The CMC sizes each opening based on appliance input and whether air comes from indoors or outdoors.2022 California Mechanical Code (CMC)

Type B gas vent is designed to vent the products of combustion from which appliances?

• a.Oil-fired only
• b.Listed gas appliances with draft hoods or Category I equipment✓
• c.Solid-fuel wood stoves
• d.High-temperature incinerators

Type B vent is a double-wall metal vent listed for venting listed gas appliances that produce relatively low-temperature, non-condensing flue gases, such as Category I furnaces. It must not be used with appliances that produce condensing or high-temperature flue products. Proper vent selection is required by the CMC.2022 California Mechanical Code (CMC)

A high-efficiency condensing furnace (Category IV) is typically vented with what material?

• a.Type B double-wall metal vent
• b.Single-wall galvanized pipe
• c.Listed PVC or CPVC plastic pipe✓
• d.Masonry chimney only

Condensing furnaces cool flue gases below their dew point, producing acidic condensate and low-temperature exhaust, so they are vented with listed plastic pipe such as PVC or CPVC. Metal Type B vent would corrode and is not rated for positive-pressure condensing appliances. Manufacturer instructions specify approved materials and lengths.2022 California Mechanical Code (CMC)

Why must condensate from a condensing furnace or cooling coil be routed to an approved drain?

• a.To increase system efficiency
• b.To prevent water damage and dispose of condensate safely✓
• c.To raise refrigerant subcooling
• d.To supply combustion air

Cooling coils and condensing furnaces generate liquid condensate that must drain to an approved location to prevent overflow, water damage, and microbial growth. The CMC requires proper slope, trapping where needed, and a secondary drain or float switch in many installations. Improper drainage is a common cause of ceiling damage.2022 California Mechanical Code (CMC)

A secondary condensate drain pan or float switch is typically required when an air handler is installed where?

• a.In a detached garage
• b.In a basement with a floor drain
• c.In an attic or above a finished ceiling where leakage would cause damage✓
• d.On a ground-level slab outdoors

When an air handler is located above a finished space, such as in an attic, code requires a secondary means of protection like an auxiliary drain pan or a float switch. These devices catch or shut off the system if the primary drain clogs. This prevents costly water damage to ceilings below.2022 California Mechanical Code (CMC)

When brazing refrigerant copper line sets, dry nitrogen is flowed through the tubing to accomplish what?

• a.Add refrigerant charge
• b.Prevent oxidation and scale formation inside the tubing✓
• c.Increase joint temperature
• d.Test the thermostat

Flowing a small amount of dry nitrogen through the lines during brazing displaces oxygen and prevents the formation of copper oxide scale inside the tubing. That scale can break loose and clog metering devices or contaminate the system. This practice protects the refrigerant circuit.

Refrigerant suction lines on a split system are typically insulated for what reason?

• a.To add structural support
• b.To prevent refrigerant leaks
• c.To reduce heat gain and prevent condensation on the cold line✓
• d.To increase line pressure

The suction line carries cold, low-pressure vapor, so it is insulated to limit heat gain that would reduce efficiency and to prevent surface condensation that drips and causes damage. The insulation should be continuous and properly sized. The liquid line is usually left uninsulated unless exposed to extreme heat.

What is the purpose of maintaining manufacturer-specified clearances to combustibles around a furnace?

• a.To improve airflow measurement
• b.To prevent overheating of nearby combustible materials and reduce fire risk✓
• c.To lower the refrigerant charge
• d.To allow duct expansion only

Listed clearances to combustibles ensure the heat radiating from the furnace and vent does not ignite nearby wood, drywall paper, or stored materials. These clearances are set by the appliance listing and the CMC. Maintaining them and service access is required for safe operation.2022 California Mechanical Code (CMC)

A properly installed refrigerant line set should have the liquid line and suction line sized according to what?

• a.The color of the insulation
• b.The length of the thermostat wire
• c.The manufacturer's specifications for the system capacity and line length✓
• d.The size of the electrical breaker

Line-set diameters are selected from manufacturer tables based on system tonnage, total line length, and vertical rise. Incorrect sizing causes oil-return problems, capacity loss, or excessive pressure drop. Following the specifications ensures proper refrigerant and oil flow.

On a long vertical suction riser, what feature helps ensure compressor oil returns properly?

• a.A larger condensate trap
• b.Correct line sizing to maintain adequate refrigerant velocity✓
• c.Extra thermostat wire
• d.A bigger air filter

Oil circulates with the refrigerant and must be carried back to the compressor by adequate vapor velocity, especially in vertical suction risers. If the line is oversized, velocity drops and oil pools, starving the compressor of lubrication. Proper sizing, and traps where required by the manufacturer, maintain oil return.

In a split-system heat pump, the outdoor coil functions as the condenser during which mode?

• a.Heating mode
• b.Defrost mode
• c.Cooling mode✓
• d.Emergency heat mode

In cooling mode the outdoor coil rejects heat and acts as the condenser, while the indoor coil absorbs heat as the evaporator. In heating mode the reversing valve swaps these roles. Understanding this reversal is key to installing and servicing heat pumps.

What is the function of the reversing valve in a heat pump?

• a.To meter refrigerant into the evaporator
• b.To change the direction of refrigerant flow between heating and cooling✓
• c.To drain condensate
• d.To regulate gas pressure

The reversing valve redirects refrigerant flow so the same equipment can both heat and cool by switching which coil is the condenser and which is the evaporator. It is energized or de-energized depending on the manufacturer's design. A stuck valve is a common heat-pump service issue.

A package unit differs from a split system in what way?

• a.It has no compressor
• b.It cannot be used for cooling
• c.All major components are contained in a single outdoor cabinet✓
• d.It requires no ductwork

In a packaged unit the compressor, condenser, evaporator, and blower are housed in one cabinet, usually on a roof or slab, connected to the building by ductwork. A split system separates the indoor and outdoor sections and connects them with a refrigerant line set. Each configuration has different installation requirements.

Gas piping for a furnace must be sized primarily to do what?

• a.Match the refrigerant line size
• b.Deliver adequate gas volume at the required pressure to all connected appliances✓
• c.Reduce electrical load
• d.Support the condensate drain

Gas pipe is sized from tables using the appliance input in BTU/hr, the pipe length, and the allowable pressure drop so every appliance receives adequate fuel. Undersized piping starves burners and causes poor combustion. The CMC provides sizing tables and requirements.2022 California Mechanical Code (CMC)

What is the purpose of a sediment trap (drip leg) installed near a gas appliance?

• a.To regulate gas pressure
• b.To vent excess gas
• c.To catch moisture and debris before they enter the appliance control valve✓
• d.To measure gas flow

A sediment trap, or drip leg, is a short vertical section that captures moisture, rust, and debris carried in the gas stream before they reach the appliance gas valve. This protects the valve and burner orifices from clogging. The CMC requires it on many appliance connections.2022 California Mechanical Code (CMC)

Before a new furnace's electrical connections are energized, the technician should verify what first?

• a.The condensate is flowing
• b.Correct voltage, polarity, and secure grounding per the wiring diagram✓
• c.The refrigerant subcooling
• d.The duct insulation R-value

Verifying supply voltage, proper polarity, and a secure ground before energizing protects the equipment controls and the technician. Loose or reversed connections can damage the board or create a shock hazard. The unit's wiring diagram and nameplate provide the required values.

Flexible duct connectors at the air handler are commonly used to accomplish what?

• a.Increase static pressure
• b.Filter the supply air
• c.Reduce the transmission of vibration and noise into the duct system✓
• d.Add refrigerant capacity

A flexible canvas or fabric connector between the unit and rigid ductwork isolates blower vibration and reduces noise transmitted into the structure. It also accommodates slight misalignment. It must be installed without restricting airflow.

Why should supply and return ducts be sealed with mastic or listed tape at joints?

• a.To increase gas pressure
• b.To prevent air leakage that wastes energy and reduces delivered airflow✓
• c.To hold refrigerant
• d.To support the furnace weight

Sealing duct joints with mastic or UL-listed tape prevents conditioned air from leaking into unconditioned spaces, which wastes energy and starves rooms of airflow. Leaky returns can also draw in dust or combustion products. California energy standards require duct sealing and testing.

When installing a split-system condenser, adequate clearance around the unit is needed mainly to ensure what?

• a.Lower electrical usage
• b.Correct refrigerant type
• c.Unrestricted airflow across the condenser coil and service access✓
• d.Reduced thermostat wire length

The condenser must draw ambient air freely across its coil to reject heat; obstructions raise head pressure and cut capacity. Clearance also allows access for service and maintenance. Manufacturer instructions specify minimum distances from walls and other units.

A furnace installed in an upflow configuration discharges heated air in which direction?

• a.Downward through the bottom
• b.Upward through the top of the cabinet✓
• c.Horizontally to the side
• d.Directly outdoors

An upflow furnace pulls return air in at the bottom and discharges heated supply air out the top, typical for basement or closet installations with overhead ductwork. Downflow and horizontal furnaces are oriented for other duct arrangements. The airflow direction must match the duct layout.

A furnace located in an attic generally requires what for code-compliant service?

• a.No access needed
• b.A refrigerant recovery machine
• c.A passageway, working platform, and light near the appliance✓
• d.A second gas meter

The CMC requires attic-installed appliances to have a solid passageway to the unit, a level service platform in front of it, and a light with a switch for safe servicing. These provisions protect technicians and allow proper maintenance. Access dimensions are specified in the code.2022 California Mechanical Code (CMC)

The condensate drain line from a cooling coil is often fitted with a trap to accomplish what?

• a.Add refrigerant
• b.Prevent air from being pulled through the drain and allow proper condensate flow✓
• c.Increase blower speed
• d.Filter the return air

A properly sized trap on a draw-through coil prevents the blower's negative pressure from either holding water in the pan or pulling air backward through the drain. This allows condensate to flow freely to the drain. The trap depth is based on the unit's static pressure.

What is the recommended practice for supporting horizontal refrigerant and drain lines?

• a.Leave them unsupported
• b.Support only at the equipment
• c.Provide supports at intervals to prevent sagging and maintain proper drain slope✓
• d.Bury them without protection

Adequate, evenly spaced supports keep refrigerant lines from sagging and vibrating and maintain the continuous downward slope required for condensate drainage. Sagging drain lines create traps that hold water and cause overflow. Support intervals follow manufacturer and code guidance.

Before releasing refrigerant charge into a newly installed line set, the system should be tested and then processed how?

• a.Charged immediately without testing
• b.Pressure tested for leaks, then evacuated to remove moisture and non-condensables✓
• c.Filled with water
• d.Left open to atmosphere

Best practice is to pressure test the assembled line set for leaks, then pull a deep vacuum to remove moisture and non-condensable gases before charging. Moisture left inside can freeze at the metering device and form acids. Only after a proper evacuation should refrigerant be introduced.

A gas furnace flue must terminate where?

• a.Inside the attic
• b.Into an open crawl space
• c.At an approved location outdoors with required clearances from openings✓
• d.Into the return duct

Flue and vent terminations must discharge outdoors at listed heights and clearances from windows, doors, and air intakes to prevent flue gases from re-entering the building. The CMC and appliance listing specify these termination requirements. Improper termination risks carbon monoxide entry.2022 California Mechanical Code (CMC)

When connecting line-voltage power to an air conditioner, the disconnect switch must be located where?

• a.Inside the electrical panel only
• b.Within sight of and readily accessible to the outdoor unit✓
• c.In the attic
• d.Behind the condenser coil

A readily accessible disconnecting means within sight of the outdoor unit allows a technician to safely de-energize the equipment for service. This is both a code requirement and a safety best practice. The disconnect is sized for the unit's electrical load.

What is the purpose of a filter drier installed in the liquid line?

• a.To meter refrigerant
• b.To insulate the line
• c.To remove moisture and trap contaminants circulating in the refrigerant✓
• d.To increase suction pressure

A liquid-line filter drier adsorbs moisture and captures particulate contaminants, protecting the metering device and compressor. It is typically replaced whenever the system is opened for major service. A saturated drier can restrict flow and should be changed.

Return air for a gas furnace must not be taken from which location?

• a.A hallway
• b.A garage or other space where it could pick up combustion products or flammable vapors✓
• c.A conditioned bedroom
• d.A central living room

Drawing return air from a garage, furnace room, or similar space risks pulling in carbon monoxide, fuel vapors, or other contaminants and distributing them through the home. The CMC prohibits return openings in these locations. Return air must come from conditioned, safe spaces.2022 California Mechanical Code (CMC)

When mounting an outdoor condenser on a slab, the pad should be installed how?

• a.Sloped steeply toward the building
• b.Level and on a stable base that keeps the unit off the ground✓
• c.Directly on loose soil
• d.Tilted so condensate pools under it

The condenser pad should be level and set on a firm, stable base so the unit sits securely and drains properly, avoiding settling that stresses the line set. A level unit also ensures correct oil return and fan operation. The pad keeps the cabinet off wet ground and debris.

In the basic refrigeration cycle, which component absorbs heat from the conditioned space?

• a.The condenser
• b.The evaporator✓
• c.The compressor
• d.The metering device

The evaporator is where low-pressure liquid refrigerant boils and absorbs heat from the indoor air, cooling the space. The condenser then rejects that heat outdoors. This heat-absorption step is the cooling effect of the system.

What is the primary function of the compressor in the refrigeration cycle?

• a.To absorb heat from the space
• b.To meter refrigerant into the evaporator
• c.To raise the pressure and temperature of the refrigerant vapor and circulate it✓
• d.To drain condensate

The compressor draws in low-pressure vapor from the evaporator and compresses it to a high pressure and temperature, then discharges it to the condenser. This pressure difference drives refrigerant flow around the loop. It is often called the heart of the system.

The condenser in an air-conditioning system performs which function?

• a.Absorbs heat and boils refrigerant
• b.Rejects heat and condenses refrigerant vapor into liquid✓
• c.Meters refrigerant flow
• d.Filters the air

In the condenser, high-pressure, high-temperature vapor gives up heat to the outdoor air and condenses into a high-pressure liquid. This heat rejection is what allows the cycle to remove heat from indoors. Airflow across the condenser coil is essential for this process.

A thermostatic expansion valve (TXV) controls refrigerant flow into the evaporator to maintain what?

• a.Constant condenser pressure
• b.Constant compressor speed
• c.A relatively constant evaporator superheat✓
• d.Constant subcooling

A TXV modulates refrigerant flow to hold a stable superheat at the evaporator outlet, matching flow to the load. This keeps the coil fed efficiently and protects the compressor from liquid floodback. It responds to the temperature and pressure of the suction line.

Superheat is defined as the temperature of the refrigerant vapor above what?

• a.Its condensing temperature
• b.Its saturation (boiling) temperature at the existing pressure✓
• c.The outdoor ambient temperature
• d.The compressor discharge temperature

Superheat is the number of degrees the refrigerant vapor has been heated above its saturation temperature for the measured pressure. Adequate superheat ensures only vapor, not liquid, returns to the compressor. Technicians measure it to evaluate evaporator charge and load.

A technician measures a suction pressure whose saturation temperature is 40 F and a suction line temperature of 52 F. What is the superheat?

• a.4 degrees
• b.8 degrees
• c.12 degrees✓
• d.20 degrees

Superheat equals the suction line temperature minus the saturation temperature: 52 F minus 40 F equals 12 degrees. This value helps confirm proper evaporator feeding and charge. Very low superheat risks liquid floodback, while very high superheat suggests underfeeding.

Subcooling is measured at which point in the system?

• a.At the evaporator outlet
• b.At the condenser outlet (liquid line)✓
• c.At the compressor suction
• d.At the filter on the return duct

Subcooling is measured at the condenser outlet by comparing the liquid line temperature to the saturation temperature for the high-side pressure. It indicates how much the liquid has cooled below its condensing point. Subcooling is a primary charging check on TXV systems.

On a system with a condensing saturation temperature of 105 F and a liquid line temperature of 95 F, what is the subcooling?

• a.5 degrees
• b.8 degrees
• c.10 degrees✓
• d.15 degrees

Subcooling equals the saturation temperature minus the liquid line temperature: 105 F minus 95 F equals 10 degrees. This is a typical target range for many TXV systems. Low subcooling can indicate an undercharge, while high subcooling can indicate an overcharge or restriction.

On a fixed-orifice (piston) system, which method is generally used to check the charge?

• a.Subcooling only
• b.The superheat method using target superheat charts✓
• c.Weighing the compressor
• d.Measuring duct static pressure

Fixed-orifice metering devices are charged by the superheat method, comparing measured superheat to a target based on indoor wet-bulb and outdoor dry-bulb temperatures. TXV systems, by contrast, are typically charged by subcooling. Using the correct method for the metering device is essential.

Under EPA Section 608, what must a technician do with refrigerant before opening most systems for service?

• a.Vent it to the atmosphere
• b.Mix it with nitrogen
• c.Recover it using certified recovery equipment✓
• d.Burn it off

Section 608 prohibits knowingly venting most refrigerants and requires recovery into approved equipment before opening a system. This protects the atmosphere and conserves refrigerant. Only certified technicians using certified equipment may perform this work.EPA Section 608

EPA Section 608 certification is required for technicians who do what?

• a.Only install ductwork
• b.Maintain, service, repair, or dispose of equipment that could release regulated refrigerants✓
• c.Only wire thermostats
• d.Only design duct systems

Section 608 requires certification for anyone who could release ozone-depleting or certain other regulated refrigerants during service, maintenance, repair, or disposal. Different certification types cover small appliances, high-pressure, and low-pressure systems. Working with refrigerant without certification is a violation.EPA Section 608

Evacuating a system with a vacuum pump primarily removes what?

• a.Refrigerant oil
• b.Copper scale
• c.Moisture and non-condensable gases such as air✓
• d.The compressor windings

A deep vacuum boils off moisture and pulls out air and other non-condensables that would otherwise raise head pressure, form acids, or cause icing at the metering device. A micron gauge verifies the target vacuum is reached and held. Proper evacuation is essential before charging.

A micron gauge is used during evacuation to measure what?

• a.Refrigerant weight
• b.The depth of vacuum in the system✓
• c.Superheat
• d.Airflow

A micron gauge measures the absolute pressure (depth of vacuum) far more precisely than a compound gauge, confirming that the system is dry and tight. Technicians pull the system down to a target micron level and perform a decay test. Failure to hold vacuum indicates moisture or a leak.

Which instrument or method is commonly used for pinpointing small refrigerant leaks?

• a.A megohmmeter
• b.A manometer
• c.An electronic leak detector or bubble solution✓
• d.A pyrometer

Electronic leak detectors sense refrigerant escaping at joints, and bubble solutions reveal leaks visibly. Ultraviolet dye is another method for hard-to-find leaks. Locating and repairing leaks is required before recharging a system.

As a general principle, adding refrigerant charge to a properly running system tends to do what to the low-side pressure?

• a.Lower it significantly
• b.Raise it✓
• c.Have no effect
• d.Reverse compressor rotation

Adding charge generally raises system pressures, including the suction (low-side) pressure, while removing charge lowers them. Technicians interpret these trends together with superheat and subcooling. Charging must be verified against manufacturer targets, not pressure alone.

A refrigerant metering device such as a fixed orifice or TXV creates what effect on the refrigerant?

• a.Raises its pressure
• b.Condenses it to liquid
• c.Causes a pressure drop so it can boil at a low temperature in the evaporator✓
• d.Superheats the vapor before the condenser

The metering device restricts flow, dropping the high-pressure liquid to a low pressure so it can boil at a low temperature and absorb heat in the evaporator. This division between high and low sides is central to the cycle. TXVs also modulate this flow to control superheat.

Which category of refrigerants is being phased down under regulations due to high global warming potential?

• a.Water-based refrigerants
• b.Many high-GWP HFC refrigerants✓
• c.Nitrogen
• d.Carbon dioxide only

Regulations at the federal and California level are phasing down high global-warming-potential HFC refrigerants in favor of lower-GWP alternatives. Technicians must stay current on approved refrigerants and handling rules. Recovery and reclamation remain required under Section 608.EPA Section 608

A compressor that is trying to compress liquid refrigerant returning from the evaporator can suffer what damage?

• a.Improved efficiency
• b.Higher superheat
• c.Slugging and mechanical damage to valves or bearings✓
• d.Lower amp draw

Liquid refrigerant is nearly incompressible, so liquid floodback or slugging can damage compressor valves, bearings, and rods. Maintaining adequate superheat prevents liquid from reaching the compressor. This is why superheat is carefully controlled.

When comparing the two sides of an operating system, the discharge line is normally which relative to the suction line?

• a.Colder and lower pressure
• b.Hotter and higher pressure✓
• c.The same temperature and pressure
• d.Filled only with liquid

The discharge line leaving the compressor carries high-pressure, high-temperature vapor, while the suction line carries low-pressure, cooler vapor returning to the compressor. Recognizing these normal conditions helps a technician diagnose faults. Abnormal readings point to charge or airflow problems.

A reciprocating compressor changes the refrigerant state by doing what?

• a.Condensing vapor to liquid
• b.Metering liquid flow
• c.Using pistons to compress low-pressure vapor into high-pressure vapor✓
• d.Boiling the refrigerant

A reciprocating compressor uses pistons driven by a crankshaft to draw in and compress refrigerant vapor, raising its pressure and temperature. Scroll and rotary compressors accomplish the same result by different mechanisms. The compressor circulates refrigerant and establishes the high and low sides.

High condenser (head) pressure with normal charge is most often caused by what?

• a.Overcharged suction line insulation
• b.Poor airflow or a dirty condenser coil✓
• c.A shorted thermostat
• d.An oversized return grille

Restricted condenser airflow, from a dirty coil, failing fan, or blocked clearance, prevents adequate heat rejection and raises head pressure. Non-condensables or overcharge can also raise head pressure. Cleaning the coil and confirming fan operation are first steps.

The saturation temperature corresponding to a measured pressure is found using what?

• a.The unit nameplate
• b.A duct calculator
• c.A pressure-temperature (PT) chart or app for the specific refrigerant✓
• d.The electrical schematic

A pressure-temperature chart lists the saturation temperature for each pressure of a given refrigerant. Technicians use it to calculate superheat and subcooling from gauge readings. Each refrigerant has its own PT relationship, so the correct chart must be used.

What is the primary function of a run capacitor on a single-phase motor?

• a.To fuse the circuit
• b.To improve motor efficiency and provide a phase shift for smoother running✓
• c.To ground the motor
• d.To measure airflow

A run capacitor stays in the circuit during operation, creating the phase shift the motor needs for efficient torque and smoother running. A weak or failed run capacitor causes low torque, overheating, and high amp draw. It is tested with a capacitance meter against its microfarad rating.

A start capacitor differs from a run capacitor in that it is designed to do what?

• a.Stay energized continuously
• b.Regulate refrigerant flow
• c.Provide a high momentary boost of starting torque, then drop out of the circuit✓
• d.Filter the supply air

A start capacitor provides a large capacitance boost to start a motor under load and is switched out by a relay once the motor is up to speed. It is not rated for continuous duty. It is used with hard-start kits and certain compressor and motor designs.

A contactor in an air-conditioning condenser performs what function?

• a.Meters refrigerant
• b.Switches line-voltage power to the compressor and fan when energized by the control circuit✓
• c.Drains condensate
• d.Adjusts blower speed

The contactor is an electrically operated switch whose coil is energized by the low-voltage control circuit, closing contacts that supply line voltage to the compressor and condenser fan. Pitted or welded contacts are a common failure. It is tested for coil continuity and contact condition.

A typical low-voltage control (thermostat) circuit in residential HVAC operates at what voltage?

• a.120 volts
• b.240 volts
• c.24 volts✓
• d.480 volts

Residential control circuits generally operate at 24 volts AC, supplied by a step-down transformer. The thermostat switches this low voltage to energize relays and contactors. Measuring 24 volts at the appropriate terminals helps confirm control-circuit operation.

If a condenser fan motor fails while the compressor keeps running, what symptom is most likely?

• a.Low head pressure
• b.Rising head pressure and possible high-pressure or overload trip✓
• c.Increased subcooling only
• d.Lower amp draw on the compressor

Without condenser airflow, heat rejection collapses and head pressure climbs quickly, often tripping a high-pressure switch or the compressor overload. The system may also lose capacity and overheat. Diagnosing a hot, non-spinning fan points to the motor or its capacitor.

Low airflow across an evaporator coil during cooling most commonly causes what?

• a.High superheat at the coil
• b.Higher supply air temperature
• c.A cold, possibly frozen coil and low suction pressure✓
• d.Higher condenser airflow

Restricted evaporator airflow, from a dirty filter, blocked coil, or weak blower, reduces heat pickup so the coil runs colder and suction pressure drops, sometimes freezing the coil. Restoring airflow by cleaning filters and coils is the first corrective step. A frozen coil should be thawed before further diagnosis.

SEER (or SEER2) is a rating that describes what?

• a.Furnace heating efficiency
• b.The seasonal cooling efficiency of air-conditioning equipment✓
• c.The refrigerant type
• d.The duct leakage rate

SEER, and the updated SEER2, express the seasonal cooling output divided by the electrical energy input, so a higher number means greater cooling efficiency. It is used to compare and select air conditioners and heat pumps. California energy standards set minimum SEER values.

AFUE is the efficiency rating used for what equipment?

• a.Air conditioners
• b.Cooling towers
• c.Gas and oil furnaces✓
• d.Duct systems

Annual Fuel Utilization Efficiency (AFUE) expresses the percentage of fuel energy a furnace converts to usable heat over a season. A 95 percent AFUE furnace delivers 95 percent of the fuel's energy as heat. It is the standard heating-efficiency metric for furnaces.

HSPF (or HSPF2) rates the seasonal efficiency of what?

• a.A gas furnace
• b.A heat pump in heating mode✓
• c.An evaporative cooler
• d.A duct booster fan

Heating Seasonal Performance Factor rates how efficiently a heat pump delivers heat over a heating season. A higher HSPF, or the updated HSPF2, means more heat per unit of electricity. It complements SEER, which rates the same unit's cooling efficiency.

A furnace that heats briefly then shuts off repeatedly before satisfying the thermostat is exhibiting what?

• a.Normal operation
• b.A refrigerant leak
• c.Short cycling✓
• d.High subcooling

Short cycling is repeated brief on-off operation before the space reaches setpoint, often caused by an overheating limit trip, a dirty flame sensor, oversizing, or restricted airflow. It wastes energy and stresses components. Diagnosis targets airflow, the limit switch, and flame sensing.

A dirty flame sensor on a modern furnace most commonly causes what symptom?

• a.Continuous cooling
• b.The burners light then shut off after a few seconds (flame loss)✓
• c.High head pressure
• d.Frozen evaporator

A flame sensor confirms flame is present; when it is coated with oxide it cannot conduct the flame-rectification signal, so the control shuts off the gas as a safety response. Cleaning the sensor typically restores operation. This is a very common no-heat service call.

When measuring the actual airflow of an installed system, which measurement helps diagnose a restrictive duct system?

• a.Refrigerant subcooling
• b.Gas manifold pressure
• c.Total external static pressure across the air handler✓
• d.Condenser saturation temperature

Measuring total external static pressure and comparing it to the blower's rating reveals whether ductwork, filters, or coils are too restrictive. High static pressure indicates undersized or dirty components limiting airflow. It is a key airflow diagnostic tool.

A capacitor that reads well below its rated microfarad value should be treated how?

• a.Left in service
• b.Replaced with one of the correct rating✓
• c.Charged with refrigerant
• d.Bypassed with a jumper

A capacitor measuring significantly below its labeled microfarad rating is weak and cannot deliver the needed phase shift, causing hard starting, overheating, and high amp draw. It should be replaced with a capacitor of the same voltage and microfarad rating. Never bypass a required capacitor.

Recommended routine maintenance to preserve airflow and efficiency includes what?

• a.Adding refrigerant every visit
• b.Replacing the compressor annually
• c.Regularly replacing or cleaning air filters and cleaning coils✓
• d.Removing the condensate trap

Routine maintenance such as changing filters, cleaning evaporator and condenser coils, and clearing condensate drains preserves airflow, capacity, and efficiency. Adding refrigerant should only follow a diagnosed leak and proper charging. Regular service prevents many common failures.

A technician measuring compressor amp draw far above the rated load amps (RLA) should suspect what?

• a.A perfectly healthy compressor
• b.A mechanical or electrical problem such as high head pressure or failing windings✓
• c.An oversized filter
• d.Low thermostat voltage

Amp draw well above the nameplate RLA indicates the compressor is overloaded, which can stem from high head pressure, low voltage, or degrading windings. Continued operation risks overheating and failure. The technician investigates head pressure, voltage, and mechanical condition.

The most likely cause of no cooling when the thermostat calls but the outdoor unit is completely silent is what?

• a.Low refrigerant subcooling
• b.A dirty air filter
• c.A loss of power, a failed contactor, or an open safety/control circuit✓
• d.Excess superheat

A silent outdoor unit on a cooling call usually points to an electrical issue: tripped breaker, blown fuse, failed contactor, or an open safety such as a float switch or high-pressure switch. The technician traces control voltage and power to isolate the fault. Refrigerant issues usually still allow the unit to run.

An ECM (electronically commutated motor) blower offers what advantage over a standard PSC motor?

• a.It requires no electricity
• b.Variable speed operation and improved energy efficiency✓
• c.It eliminates the need for ductwork
• d.It removes refrigerant charge

ECM blower motors can vary speed to maintain target airflow across changing static pressure and generally use less energy than fixed-speed PSC motors. This improves comfort and efficiency and supports California energy goals. They are diagnosed differently, often through control signals and modules.

When a heat pump is stuck in cooling on a heat call, which component is a prime suspect?

• a.The condensate trap
• b.The air filter
• c.The reversing valve or its solenoid coil✓
• d.The supply registers

If a heat pump blows cold air on a heating call, the reversing valve may be stuck or its solenoid coil or control signal may have failed, leaving the system in cooling mode. The technician checks the coil, the control voltage, and valve operation. A stuck valve often requires replacement.

Under Cal/OSHA, what is the purpose of a lockout/tagout (LOTO) procedure?

• a.To label refrigerant cylinders
• b.To isolate and secure energy sources so equipment cannot start during service✓
• c.To measure superheat
• d.To size ductwork

Lockout/tagout requires de-energizing and physically locking energy-isolating devices, then tagging them, so machinery cannot be energized while a technician services it. This protects workers from electrical shock and unexpected startup. Cal/OSHA Title 8 sets the specific requirements.Cal/OSHA Title 8

Carbon monoxide is dangerous primarily because it is what?

• a.A visible green gas
• b.A refrigerant
• c.A colorless, odorless toxic gas produced by incomplete combustion✓
• d.Heavier than refrigerant vapor

Carbon monoxide is a colorless, odorless gas produced by incomplete combustion of fuels, and it can be deadly because occupants cannot detect it. Cracked heat exchangers, poor venting, or inadequate combustion air can produce it. CO detectors and proper venting are essential safeguards.

A cracked heat exchanger in a gas furnace is a serious hazard because it can do what?

• a.Increase cooling capacity
• b.Allow combustion products including carbon monoxide to mix with the supply air✓
• c.Lower the refrigerant charge
• d.Improve airflow

A cracked heat exchanger can let flue gases, including carbon monoxide, leak into the circulating supply air and be distributed through the home. This is a life-safety hazard requiring the furnace to be shut down until repaired or replaced. Inspection for cracks is a standard safety check.

Cal/OSHA defines a confined space as one that has what characteristics?

• a.Any outdoor area
• b.Any room with a door
• c.Large enough to enter, limited means of entry or exit, and not designed for continuous occupancy✓
• d.Only spaces below ground

A confined space is large enough to bodily enter and perform work, has limited or restricted entry and exit, and is not designed for continuous occupancy, such as certain tanks, vaults, or attics. Permit-required confined spaces have added atmospheric or engulfment hazards. Cal/OSHA sets entry procedures and monitoring requirements.Cal/OSHA Title 8

When using a portable ladder, a safe practice is to maintain what?

• a.One hand on a tool at all times
• b.Three points of contact and proper ladder angle✓
• c.The ladder on a slippery surface
• d.The top rung as a step

Maintaining three points of contact and setting a straight ladder at roughly a 4-to-1 angle greatly reduces fall risk. Ladders must be on stable, level surfaces and inspected before use. Cal/OSHA specifies ladder safety requirements to prevent falls, a leading cause of injury.Cal/OSHA Title 8

Refrigerant can cause frostbite because liquid refrigerant does what when it contacts skin?

• a.Warms the skin
• b.Acts as a mild lotion
• c.Rapidly evaporates and absorbs heat, freezing tissue✓
• d.Has no effect

Liquid refrigerant boils at very low temperatures at atmospheric pressure, so contact with skin or eyes rapidly absorbs heat and can cause frostbite. Technicians wear gloves and eye protection when handling refrigerant. Cylinders and lines must be handled carefully to avoid sudden releases.

Refrigerant cylinders should be stored and handled how?

• a.In direct sunlight above their rated temperature
• b.Secured upright, away from heat, and never overfilled✓
• c.Laid on their side near a flame
• d.Vented periodically to relieve pressure

Refrigerant cylinders must be kept below their rated temperature, secured to prevent falling, and never overfilled, because heat raises internal pressure dangerously. Overheating or overfilling can cause a cylinder to rupture. Proper storage and handling are basic refrigerant safety practices.

The California Mechanical Code (CMC) primarily governs what?

• a.Electrical wiring only
• b.Plumbing fixtures only
• c.The installation of heating, ventilation, air-conditioning, and refrigeration systems✓
• d.Structural framing

The CMC sets the rules for installing mechanical systems including furnaces, air conditioners, ventilation, and refrigeration, covering venting, combustion air, clearances, and equipment access. Electrical work falls under the CEC and plumbing under the CPC. Contractors coordinate across these codes.2022 California Mechanical Code (CMC)

The California Electrical Code (CEC) is the governing code for what portion of HVAC work?

• a.Gas venting
• b.Electrical wiring, disconnects, grounding, and circuit protection✓
• c.Condensate drainage
• d.Combustion air openings

The CEC governs the electrical aspects of HVAC installations, including circuit sizing, disconnecting means, grounding, and overcurrent protection. Proper electrical work protects against shock and fire. HVAC technicians must follow the CEC for all power and control wiring.

Under the California Plumbing Code, condensate waste from HVAC equipment is generally treated as what?

• a.Potable water
• b.Fuel gas
• c.Drainage that must discharge to an approved location✓
• d.Combustion air

HVAC condensate is drainage governed by the California Plumbing Code and must terminate at an approved point, not create a nuisance or hazard. Improper discharge onto walkways or into unapproved locations is a violation. Proper drainage prevents damage and slip hazards.2022 California Mechanical Code (CMC)

Personal protective equipment (PPE) commonly required when brazing refrigerant lines includes what?

• a.Only a dust mask
• b.Eye protection and appropriate gloves, with attention to ventilation✓
• c.No protection is needed
• d.Hearing protection only

Brazing produces intense heat, bright light, and potentially harmful fumes, so eye protection, gloves, and adequate ventilation are needed. Nitrogen purging reduces harmful phosgene-type byproducts from certain fluxes and coatings. Cal/OSHA requires appropriate PPE for the hazards present.Cal/OSHA Title 8

Why is a carbon monoxide alarm recommended or required in dwellings with fuel-burning appliances?

• a.To detect refrigerant leaks
• b.To measure humidity
• c.To warn occupants of dangerous CO levels before they become life-threatening✓
• d.To sense high head pressure

CO alarms detect rising carbon monoxide and warn occupants because the gas is otherwise undetectable by human senses. California law requires CO alarms in most dwellings with fuel-burning appliances or attached garages. They are a critical last line of defense against CO poisoning.

Before working inside an energized electrical panel is unavoidable, a technician should do what to reduce shock risk?

• a.Wear cotton gloves only
• b.Use appropriate insulated tools and PPE and follow safe work practices✓
• c.Wet the work area
• d.Remove all covers permanently

When de-energizing is not feasible, Cal/OSHA safe work practices call for insulated tools, appropriate PPE, and careful technique to reduce shock and arc-flash risk. Whenever possible, the circuit should be de-energized and locked out first. Working live is a last resort with added precautions.Cal/OSHA Title 8

Adequate ventilation air in occupied buildings is important because it does what?

• a.Increases refrigerant charge
• b.Reduces duct static pressure
• c.Provides fresh outdoor air to dilute indoor contaminants and maintain air quality✓
• d.Lowers the SEER rating

Ventilation introduces outdoor air to dilute odors, carbon dioxide, and other indoor contaminants, maintaining acceptable indoor air quality. The CMC and related standards set minimum ventilation rates for occupancies. Balancing ventilation with energy use is part of good system design.2022 California Mechanical Code (CMC)

A furnace's high-limit (temperature limit) switch protects the equipment by doing what?

• a.Metering gas continuously
• b.Shutting off the burners if the furnace overheats✓
• c.Increasing blower speed permanently
• d.Recovering refrigerant

The high-limit switch senses excessive heat exchanger temperature, typically from low airflow, and shuts off the burners to prevent overheating and fire. Repeated tripping signals an airflow problem such as a dirty filter or failing blower. It is a key safety control that must never be bypassed.

When entering a permit-required confined space, atmospheric testing should be performed to check for what?

• a.Refrigerant color
• b.Duct dimensions
• c.Oxygen level and the presence of toxic or flammable gases✓
• d.Blower speed

Before and during entry into a permit-required confined space, the atmosphere is tested for adequate oxygen and for toxic or flammable gases to ensure it is safe. Continuous monitoring and ventilation may be required. Cal/OSHA mandates these procedures to prevent asphyxiation and explosion.Cal/OSHA Title 8

A high-pressure safety switch on refrigeration equipment protects the system by doing what?

• a.Adding refrigerant
• b.Interrupting the compressor circuit if discharge pressure becomes dangerously high✓
• c.Draining condensate
• d.Boosting the fan speed

A high-pressure switch opens the control circuit and stops the compressor when head pressure rises to an unsafe level, such as from a failed condenser fan or blocked airflow. This prevents component rupture and damage. It should be diagnosed and reset only after the underlying cause is corrected.

Which practice best reduces the risk of heat illness for HVAC technicians working on hot rooftops?

• a.Skipping water breaks to finish faster
• b.Wearing heavy dark clothing at midday
• c.Providing water, rest, and shade and pacing work during high heat✓
• d.Avoiding all fluids

Cal/OSHA heat illness prevention calls for access to water, shade, and rest breaks, plus acclimatization and pacing during high temperatures. Rooftop HVAC work exposes technicians to extreme heat, raising the risk of heat exhaustion or stroke. Recognizing symptoms early and hydrating are essential.Cal/OSHA Title 8