hvac troubleshooting
AC not cooling
Common symptoms: warm air; not cooling; ac warm; no cool
Stop and call a pro if:
- burning odor
- sparks
- smoke
- water near electrical
Step-by-step diagnostic flow
Step 1
Do you detect any burning smells, smoke, or electrical hazards?
Step 2
Is the thermostat set to Cool and a temperature below current room temp?
Step 3
Check the air filter and supply vents for blockage (visual only).
Look for heavy dust on the filter surface or blocked vents.
Step 4
Do you see ice on the refrigerant lines or evaporator housing (if visible without removing panels)?
Possible outcomes
Stop and seek professional help immediately
high confidenceSafety hazard detected.
Electrical or fire hazard present
Thermostat settings may be the cause
medium confidenceSystem not set to cool or setpoint above room temp.
Safe next steps
- Document current thermostat mode, schedule/hold, and setpoint
What to document for a pro
- Thermostat model
- Photos of settings
Likely dirty/blocked air filter or vents
high confidenceObvious restriction observed.
Safe next steps
- Photograph current filter and install date sticker
- List blocked vents/rooms
What to document for a pro
- Filter size and MERV
- Room list with weak airflow
Possible frozen evaporator coil
medium confidenceIce visible and symptoms suggest freeze-up.
Safe next steps
- Turn system off to allow thawing; do not open sealed panels
- Collect temp readings and times
What to document for a pro
- Supply/return temps and timestamps
- Photos of ice
If ice persists or returns quickly
Further professional diagnosis recommended
low confidenceNon-invasive checks inconclusive.
Safe next steps
- Capture sounds, error codes if any, and cycle timing
What to document for a pro
- Thermostat model
- System brand/model
- Breaker labels
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