Air Conditioning troubleshooting
AC Blowing Warm Air or Not Cooling? Here's Why
When the AC runs but won't cool, it's usually airflow, refrigerant, or an electrical part. A couple of checks rule out the easy stuff.
Common causes
Dirty air filter or coil
You can checkRestricted airflow from a clogged filter or evaporator coil kills cooling and can freeze the system.
Low refrigerant (leak)
Pro repairAC doesn't 'use up' refrigerant — low charge means a leak that needs EPA-certified repair.
Failed capacitor
Pro repairA bad capacitor stops the compressor or fan from starting; you may hear a hum or clicking.
Dirty outdoor condenser
You can checkA coil packed with dirt and leaves can't release heat, so the house won't cool.
What you can check yourself
- Set the thermostat to COOL and a few degrees below room temp.
- Replace the air filter.
- Gently rinse the outdoor condenser coil and clear leaves/debris around it.
- Check the breaker for the outdoor unit hasn't tripped.
When to call a pro
If airflow is clear and it still won't cool, it's usually refrigerant or a capacitor — both need a tech. We prioritize no-cool calls in summer heat.
Most air conditioner repairs run $150–$1,200 — see our repair cost guide.
Other air conditioning problems
FAQ
AC blowing warm air — questions
When the AC runs but won't cool, it's usually airflow, refrigerant, or an electrical part. A couple of checks rule out the easy stuff. The most common causes are dirty air filter or coil, low refrigerant (leak), failed capacitor.
You can safely check a few things first: Set the thermostat to COOL and a few degrees below room temp. Replace the air filter. Gently rinse the outdoor condenser coil and clear leaves/debris around it. If airflow is clear and it still won't cool, it's usually refrigerant or a capacitor — both need a tech. We prioritize no-cool calls in summer heat.
Most air conditioner repairs run $150–$1,200 in the San Francisco Bay Area, parts and labor — you get a flat-rate quote before any work begins. See our repair cost guide for details.
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