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Why is my AC running but not cooling?
A running AC that doesn't cool usually means the system is operating but not transferring heat. The most common causes are listed here.
Likely causes
| Cause | Likelihood | Severity | Cost |
|---|---|---|---|
| Low refrigerant charge | high | Medium | $200–$1,500 |
| Frozen evaporator coil | medium | Medium | $150–$600 |
| Dirty condenser coils | medium | Low | $100–$300 |
| Bad capacitor | medium | Medium | $150–$400 |
Safe checks you can do
- Check for a frozen indoor coil (ice buildup).
- Inspect outdoor condenser for dirt or obstruction.
- Verify the fan is spinning on the outdoor unit.
Emergency signals
- Frozen lines and coil
- Sizzling or grinding noises
- Tripping breaker
Next action
Turn the system off if you see ice and let it thaw. If it keeps running without cooling, schedule a technician — the most likely culprit is refrigerant or a capacitor.