AC Blowing Warm Air
Quick Answer
If your AC is blowing warm or hot air, first check that your thermostat is set correctly and the outdoor unit is running. Common causes include thermostat issues, tripped breakers, refrigerant leaks, or a dirty outdoor unit. Some fixes are simple DIY tasks.
Safe Checks You Can Do
- 1Verify thermostat settings - Make sure it's on "cool" mode, not "heat" or "fan only." Set temp at least 3 degrees below room temp.
- 2Check circuit breakers - The indoor and outdoor units have separate breakers. Reset any that have tripped.
- 3Inspect the outdoor unit - Is the fan spinning? Is the unit making any noise? Make sure it has power.
- 4Replace the air filter - A severely clogged filter can cause the system to malfunction.
- 5Clear the outdoor unit - Remove leaves, grass clippings, and debris from around the condenser.
Likely Causes
- Thermostat set incorrectly
Someone may have changed settings, or batteries are dead causing erratic behavior.
- Outdoor unit not running
If the condenser isn't on, the indoor unit just blows unconditioned air.
- Refrigerant leak
Low refrigerant means the system can't cool effectively. Professional repair required.
- Tripped breaker or blown fuse
Power issues to the outdoor unit are common, especially after storms.
- Failed capacitor or compressor
Electrical components can fail, preventing the compressor from starting.
When to Call a Pro
- The outdoor unit won't start even after resetting breakers
- You hear a humming or buzzing but the compressor doesn't start
- Refrigerant lines are icy or the system cycles on and off rapidly
- The problem started after a power outage or storm
- Basic troubleshooting hasn't resolved the issue
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