Type II — High-PressureCâu 160 / 240
After evacuating a Type II R-410A system to a deep vacuum, a technician is ready to charge. Which practice supports an accurate final charge?
a.Charge until the low-side gauge reads any positive pressure
b.Add refrigerant until frost appears on the compressor
c.Charge vapor into the liquid line while off
d.Weigh in the manufacturer's specified charge, then fine-tune using subcooling (TXV) or superheat (fixed orifice)
Giải thích
The most accurate approach is to weigh in the manufacturer's specified charge, then verify and fine-tune using subcooling on a TXV system or superheat on a fixed-orifice system. Judging by gauge pressure alone or by frost is unreliable and can lead to over- or undercharging. Blends like R-410A are charged as liquid, metered to protect the compressor.
Luyện miễn phí toàn bộ 240 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A technician performs a standing pressure (leak) test on a repaired Type II system using dry nitrogen. Over several hours the pressure holds steady with no drop. What does this indicate?
- A technician is selecting a vacuum pump to properly dehydrate a Type II R-410A system. Why is a dedicated vacuum pump used instead of the recovery machine to pull the final vacuum?
- A technician retrofitting an R-22 system to an HFC replacement changes the oil and refrigerant. Which additional component is most commonly replaced during the retrofit?
- A technician is unsure which required vacuum applies to a high-pressure appliance during recovery. Which two factors determine the required evacuation level?
- A technician recovers refrigerant from a heat pump in heating mode and is unsure which service port to use. On a heat pump, why must the technician understand the reversing valve position when recovering or charging?
- A commercial refrigeration appliance holds more than 50 pounds of an ozone-depleting refrigerant and has developed a leak. Under the Section 608 leak-repair requirements, what must the owner or operator generally do?
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