Heating & coolingUpdated September 13, 2026 · 7 min
AC Running but Not Cooling: Safe Checks and Repair Costs
An air conditioner that runs without cooling often has an airflow, thermostat, outdoor-unit, or refrigerant problem. Start with the safe checks below before arranging service.
URGENCY
Usually prompt, not emergency
TYPICAL COST
$160–$650
Safe checks you can do now
- 1Set the thermostat to Cool and at least 3°F below room temperature.
- 2Replace a visibly dirty return-air filter with the correct size.
- 3Confirm supply vents are open and not blocked by furniture.
- 4Check whether the outdoor unit is running; do not open its cabinet.
Common causes
Restricted airflow
A clogged filter or blocked coil reduces cooling and can cause ice.
Failed capacitor
The outdoor fan or compressor may hum but struggle to start.
Low refrigerant
A leak can reduce cooling and may create ice on the refrigerant line.
Call a professional when
- The outdoor unit buzzes but the fan does not turn.
- Ice returns after the system has fully thawed.
- The breaker trips again after one reset.
Related home repair guides
FIXAVUE provides general educational information, not a diagnosis or substitute for an on-site inspection. Call 911 for immediate danger.