Why should the hermetic compressor not be started yet?
Safety · EPA 608 Type II. The correct answer, and the reasoning behind it.
Hermetic compressors under vacuum and other high-pressure hazards.
The question
An R-410A system has just been evacuated to a deep vacuum after a repair. Why should the hermetic compressor not be started yet?
- Running it under vacuum can damage the motorCorrect answer
- It will cool the system too fast
- It will void the recovery machine's certification
- It will raise the system's superheat
Why “Running it under vacuum can damage the motor” is correct
EPA's outline says hermetic compressors should not be energized under vacuum. In a deep vacuum the motor windings lose the insulating effect of the surrounding gas, and the motor can arc and burn out.
Source: EPA: Test Topics
Why the other answers are wrong
- It will cool the system too fast — Cooling speed is not the hazard.
- It will void the recovery machine's certification — Recovery machine certification is not affected.
- It will raise the system's superheat — Superheat is not what makes this dangerous.
Practice more of this
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Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.