General troubleshooting guides

44 guides. Problems that apply to any equipment. Each one lists the likely causes and what to check, in order.

All brands (44)

• Bacteria/algae/scale in reservoir
  Possible causes and checks for: bacteria/algae/scale in reservoir.
• CO present
  Possible causes and checks for: co present.
• Condensation on windows/walls in cold weather
  Possible causes and checks for: condensation on windows/walls in cold weather.
• Condensation on windows/walls, peeling paint
  Possible causes and checks for: condensation on windows/walls, peeling paint.
• Corroded duct joints
  Possible causes and checks for: corroded duct joints.
• Crystallization / solidification
  Possible causes and checks for: crystallization / solidification.
• Damper stuck open/closed
  Possible causes and checks for: damper stuck open/closed.
• Defrost ineffective or too slow; drain refreezes
  Possible causes and checks for: defrost ineffective or too slow; drain refreezes.
• Dirt streaks on walls/ceiling near grilles
  Possible causes and checks for: dirt streaks on walls/ceiling near grilles.
• Draft complaints
  Possible causes and checks for: draft complaints.
• Drain frozen / flooding
  Possible causes and checks for: drain frozen / flooding.
• Flash gas in liquid line (bubbles in sight glass with full charge) / frost-back on suction
  Possible causes and checks for: flash gas in liquid line (bubbles in sight glass with full charge) / frost-back on suction.
• Frosted suction line
  Possible causes and checks for: frosted suction line.
• High filter pressure drop
  Possible causes and checks for: high filter pressure drop.
• Leak
  Possible causes and checks for: leak.
• Leak check false alarms near foam insulation
  Possible causes and checks for: leak check false alarms near foam insulation.
• Low airflow / rooms starved at end of runs
  Possible causes and checks for: low airflow / rooms starved at end of runs.
• Low capacity
  Possible causes and checks for: low capacity.
• Low output
  Possible causes and checks for: low output.
• Moisture indicator shows wet
  Possible causes and checks for: moisture indicator shows wet.
• Monthly check
  Possible causes and checks for: monthly check.
• Musty odor, mold
  Possible causes and checks for: musty odor, mold.
• Negative pressure / drafts / spillage
  Possible causes and checks for: negative pressure / drafts / spillage.
• No defrost
  Possible causes and checks for: no defrost.
• No heat — low-voltage stat diagnostic (16 steps)
  Possible causes and checks for: no heat — low-voltage stat diagnostic (16 steps).
• No heating
  Possible causes and checks for: no heating.
• Noisy ductwork
  Possible causes and checks for: noisy ductwork.
• Occupant symptoms clear when away (SBS)
  Possible causes and checks for: occupant symptoms clear when away (sbs).
• Oil foaming at start
  Possible causes and checks for: oil foaming at start.
• One radiator cold
  Possible causes and checks for: one radiator cold.
• Purge runs > 2–3 minutes per cycle
  Possible causes and checks for: purge runs > 2–3 minutes per cycle.
• Rooms at different temps / stratification
  Possible causes and checks for: rooms at different temps / stratification.
• Runs but not pumping
  Possible causes and checks for: runs but not pumping.
• Second stage never comes on
  Possible causes and checks for: second stage never comes on.
• Shuts off, won't run
  Possible causes and checks for: shuts off, won't run.
• Stale/stuffy, fatigue, headaches
  Possible causes and checks for: stale/stuffy, fatigue, headaches.
• Trouble light on / ozone smell / dusty rooms / constant arcing
  Possible causes and checks for: trouble light on / ozone smell / dusty rooms / constant arcing.
• Ultrasonic detector alarms
  Possible causes and checks for: ultrasonic detector alarms.
• Uncomfortable building / high energy use
  Possible causes and checks for: uncomfortable building / high energy use.
• Valve not responding / wrong superheat
  Possible causes and checks for: valve not responding / wrong superheat.
• Valve won't open/close
  Possible causes and checks for: valve won't open/close.
• Water not heating / high head when in reclaim
  Possible causes and checks for: water not heating / high head when in reclaim.
• Wide temperature swing / overshoot / lag
  Possible causes and checks for: wide temperature swing / overshoot / lag.
• Zone not conditioning — overall procedure
  Possible causes and checks for: zone not conditioning — overall procedure.

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.