Type II — High-PressureQuestion 150 of 240
A technician replaces a leaking evaporator on an R-410A system and must protect the new POE oil during the repair. Why is POE oil handling important?
a.POE oil is flammable at room temperature and must be kept frozen
b.POE oil is highly hygroscopic and absorbs moisture from the air quickly, so the system should be kept sealed and evacuated well
c.POE oil never needs a vacuum because it repels water
d.POE oil can be mixed freely with mineral oil with no effect
Explanation
Polyolester (POE) oil used with R-410A is very hygroscopic, meaning it absorbs moisture from the air rapidly, so the system should be left open as briefly as possible and evacuated to a deep vacuum. Excess moisture can cause acid formation and system damage. POE and mineral oil are not freely interchangeable, which matters during retrofits and repairs.
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