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Compressor won't start (general procedure)

What is going on

Possible causes and checks for: compressor won't start (general procedure).

Likely causes

  • No power at compressor
  • Relay/overload
  • Motor
  • External circuit

Check in this order

  1. Confirm voltage at compressor
  2. Check relay & protectors
  3. Disconnect all wiring
  4. Manual test cord (with new caps for CSIR/CSCR) — runs = external fault (wiring/stat/relay/overload)
  5. Doesn't = replace compressor

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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.