Electrical troubleshooting guides

15 guides. Motors, controls, relays and wiring problems. Each one lists the likely causes and what to check, in order.

All brands (15)

• Any circuit fault — classify the problem
  Load dead, breaker trips, fuse blows, shocks, low voltage at load.
• Contacts open when they should be closed
  Possible causes and checks for: contacts open when they should be closed.
• Diode test
  Rectifier/board DC supply missing.
• Element overheats/burns open
  Possible causes and checks for: element overheats/burns open.
• Fuse blows / breaker trips repeatedly
  Possible causes and checks for: fuse blows / breaker trips repeatedly.
• Generic circuit diagnosis questions
  Possible causes and checks for: generic circuit diagnosis questions.
• House too humid
  Possible causes and checks for: house too humid.
• Hums but will not start
  Possible causes and checks for: hums but will not start.
• Motor dead with proper voltage
  Possible causes and checks for: motor dead with proper voltage.
• Motor overheats / trips overload
  Possible causes and checks for: motor overheats / trips overload.
• No heat — line-voltage stat
  Possible causes and checks for: no heat — line-voltage stat.
• No power / low voltage
  Possible causes and checks for: no power / low voltage.
• Noisy motor / knock / vibration
  Possible causes and checks for: noisy motor / knock / vibration.
• Reads 24 V or less / transformer failing
  Possible causes and checks for: reads 24 v or less / transformer failing.
• Single phasing (one fuse/breaker open)
  Motor runs hot, may burn out; phase-loss monitor trips.

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.