A closer look
Running equipment does not always mean cooling
A fan can run while the cooling side of the system is not operating correctly. Checking thermostat settings and an accessible filter can be useful, but repeated no-cooling calls need a diagnosis of the system as a whole.
We consider airflow, indoor and outdoor operation, controls and other checks relevant to the symptoms. Refrigerant is not a routine consumable; a suspected shortage needs investigation rather than an automatic top-off.
Common reasons an AC runs but does not cool
- Dirty air filter restricting airflow
- Dirty outdoor condenser coil
- Low refrigerant caused by a leak
- Frozen evaporator coil
- Failed capacitor or condenser fan motor
- Thermostat set incorrectly or failing
- A system that is too small for the house or has aged out
Quick checks before you call
- Confirm the thermostat is set to Cool with a temperature below the room temperature
- Replace a dirty filter
- Look for ice on the indoor unit or refrigerant line
- Make sure the outdoor unit is running and its fan is spinning
When to call a technician
If the basics do not fix it, or you see ice, hear unusual noises, or the outdoor unit is not running, turn the system off and call. Low refrigerant and electrical failures are not homeowner repairs.