EPA Section 608 Universal Certification ExamType I (Small Appliances)Easy
A technician is installing a new compressor in a small appliance that uses R-134a. After replacing the compressor, what is the primary purpose of evacuating the system to a deep vacuum?
- ATo test the system for leaks before charging.
- BTo remove any remaining refrigerant from the system.
- CTo dehydrate the system by removing non-condensable gases and moisture.
- DTo verify the proper operation of the new compressor.
Show answer & explanationAnswer & explanation
Correct answer: C. To dehydrate the system by removing non-condensable gases and moisture.
Evacuating to a deep vacuum removes air (non-condensable gases) and moisture from the system. Moisture can combine with refrigerant to form corrosive acids, while air increases head pressure and reduces efficiency.
Why the other options are wrong
- A. While a vacuum can indicate a gross leak, its primary purpose is not leak testing.
- B. Recovery removes most refrigerant; evacuation is for residual contaminants.
- D. Compressor operation is checked after charging, not during evacuation.
Deep Vacuum Purpose
The primary goal of pulling a deep vacuum on an HVAC/R system is to remove non-condensable gases (like air) and moisture.
- Moisture causes acid formation.
- Non-condensables increase system pressure.
- Ensures system purity for optimal performance.
- Achieved with a vacuum pump.
Memory trick: Vacuum deep, keep system clean and neat!