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.Weigh in the manufacturer's specified charge, then fine-tune using subcooling (TXV) or superheat (fixed orifice)
b.Charge until the low-side gauge reads any positive pressure
c.Add refrigerant until frost appears on the compressor
d.Charge vapor into the liquid line while off
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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