Type II — High-PressureQuestion 160 of 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)
Explanation
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.
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