Type II — High-PressureQuestion 127 of 240
After replacing a compressor on an R-410A system, a technician needs to remove moisture and noncondensables before charging. Which procedure is the correct way to dehydrate the system?
a.Purge the system with R-410A vapor and vent it
b.Pressurize with oxygen and hold overnight
c.Blow shop air through the lines until dry
d.Deep vacuum verified by a micron gauge
Explanation
Proper dehydration means pulling a deep vacuum with a vacuum pump and confirming the level with a micron gauge; triple evacuation (evacuate, break vacuum with dry nitrogen, repeat) is used to remove stubborn moisture. Purging with refrigerant is illegal venting, and oxygen must never be used because it can cause an explosion with oil. Shop air introduces moisture and noncondensables.
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