Why is my AC not cooling?
An air conditioner that runs but doesn't cool is most often suffering from restricted airflow — a clogged filter or a frozen indoor coil — or has lost refrigerant through a leak. If the outdoor unit hums but the fan doesn't spin, that's usually a failed capacitor, which is a quick repair but not a safe one to attempt yourself.
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What you can safely check
- Filter
- The single most common cause. A blocked filter starves the coil and can freeze it solid.
- Look for ice
- Ice on the refrigerant lines or indoor coil means shut the system off and switch the fan to ON to thaw it. Running a frozen system damages the compressor.
- Outdoor unit
- Clear grass clippings, leaves and debris from the fins, and keep two feet of space around it.
- Vents and returns
- Closed or furniture-blocked vents starve the system and cause uneven cooling.
What’s probably going on
- Low refrigerant from a leak
- Refrigerant isn't consumed — if it's low, it leaked. Topping up without finding the leak means paying twice.
- Failed capacitor
- A humming outdoor unit with a still fan is the classic sign. Capacitors hold a charge even with power off.
- Dirty condenser coil
- The outdoor coil sheds heat. Caked in cottonwood or dust, it can't, and capacity falls off.
- Failing compressor
- The expensive one. Often preceded by months of weak cooling that went unaddressed.
Stop here and call
Don't open the outdoor disconnect or the electrical panel on the unit. Capacitors store a dangerous charge long after the power is off.
What we do about it
We measure superheat and subcooling to tell an airflow problem from a refrigerant one, leak-search rather than just top up, and test the electricals under load.
Still stuck?
Tell us what the system is doing and we’ll tell you what it takes to fix — free quotes, no obligation, and a straight answer about whether it’s worth repairing.