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SESK: Stuff Everyone Should Know · sesk.info/epa-no-energize-hermetic-under-vacuum

What should a technician never do with a hermetic compressor while it is under a vacuum?

Never energize a hermetic compressor under vacuum.

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  1. Energize it ✔
  2. Insulate it
  3. Label it

Why: EPA's Type II safety topics say not to energize hermetic compressors under vacuum. Powering one up while the system is evacuated is unsafe.

Huh, didn't know that: Type II safety topics also include equipment room requirements under ASHRAE Standard 15, including an oxygen deprivation sensor.

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References

Answer: Energize it. EPA's Type II safety topics say not to energize hermetic compressors under vacuum. Powering one up while the system is evacuated is unsafe.

  1. EPA Section 608 Technician Certification Test Topics www.epa.gov/section608/test-topics
    Shouldn't energize hermetic compressors under vacuum
    Checked 2026-10-10.
  2. EPA Section 608 Technician Certification Test Topics www.epa.gov/section608/test-topics
    oxygen deprivation sensor with all refrigerants
    Checked 2026-10-10.

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