An air conditioner that runs without cooling is one of the most common summer calls. Some causes are simple enough to check yourself; others need a technician. Run through these in order before you pick up the phone.
Check these first
- The thermostat: Confirm it is set to "cool" and below room temperature, and that the fan is set to "auto" rather than "on" (which blows air even when it is not cooling).
- The air filter: A clogged filter is the number-one DIY cause. It chokes airflow so badly the system cannot move cool air — or freezes up entirely. Replace it and give the system time.
- The vents: Make sure supply and return vents are open and unblocked by furniture or rugs.
- The outdoor unit: Check that the outside condenser is not smothered by leaves, grass clippings, or debris, and that the fan is spinning when the system runs.
- The breaker: Confirm the outdoor unit's breaker has not tripped.
The frozen-coil trap
If you find ice on the refrigerant lines or indoor coil, turn the system to "off" and just run the fan to thaw it, then replace the filter. A frozen coil is usually caused by restricted airflow or low refrigerant — the first you can fix, the second needs a pro.
When to call
If the basics check out and the house still won't cool, the likely culprits — low refrigerant, a failing compressor, a bad capacitor, or electrical faults — are technician territory. These are not DIY repairs, and guessing at them can make things worse. Smith's AC repair team diagnoses the real problem and gives you honest options.
Frequently asked questions
Why is my AC running but not cooling?
Start with the simple checks: thermostat set to cool and fan on auto, a clean air filter, open and unblocked vents, a clear outdoor condenser, and a breaker that has not tripped. A clogged filter alone causes a real share of these calls.
What should I do if my AC coil is frozen?
Turn the system to off and run only the fan to thaw the ice, then replace the filter. A frozen coil is usually caused by restricted airflow or low refrigerant — the first you can fix, the second needs a technician.
When should I call a technician for an AC that won't cool?
If the basic checks are fine and the house still won't cool, the likely causes — low refrigerant, a failing compressor, a bad capacitor, or electrical faults — are technician territory and not safe DIY repairs.