Homeowner question
AC running but not cooling or blowing warm air?
Updated
Short answer
Start with the thermostat: Cool mode, set below room temperature, fan on Auto. Then check the air filter and the breakers, including the disconnect by the outdoor unit. If the vents still blow warm air, or ice shows on the copper lines, turn cooling off and call.
In a South Fulton July, with afternoons near 90F and air you can wear, an AC that runs without cooling turns a house sticky by dinner. This page covers what you can safely check, what to leave alone, and when to call.
Find the symptom that matches yours in the table, read the likely cause, then see whether it's a check for you or for a technician.
| What you notice | Likely cause | Who should handle it |
|---|---|---|
| Warm air from the supply vents | Thermostat setting, dirty filter or low refrigerant | You first, then tech |
| Ice on the copper lines or coil | Starved airflow or a low refrigerant charge | Turn off, call tech |
| Outdoor fan still or unit humming | Failed capacitor, contactor or fan motor | A technician, not you |
| Water in the pan or wet ceiling | Clogged condensate drain or a melting coil | Turn off, call tech |
Why is my AC running but not cooling enough?
When an AC runs but blows warm air in a South Fulton house, it nearly always comes down to one of three things. Air isn't moving across the indoor coil, the outdoor unit isn't doing its half, or the refrigerant side is short. The first is often just a filter.
No. If the system is low there is a leak. Topping up without finding the leak will only cause it to break down again. Refrigerant requires an EPA section 608 exam. This is not a job for a homeowner. Existing R-410A systems can still be serviced.
Should I turn my AC off if it's not cooling?
Yes. If you can see ice or water. Or if the outside unit is humming but the fan isn't turning. The coil will be starved causing it to freeze. The compressor works hard for no cooling. A blocked drain under an attic unit can overflow. We see plenty of these in South Fulton.
Safety first
If ice is on the lines or the indoor coil, turn the system off at the thermostat. Never open the outdoor unit's electrical panel. Capacitors inside hold a charge even with the power off.
Switch cooling off, set the fan to On and let the ice melt, often for hours. Put a towel under the indoor unit, then call so the cause gets found. We take South Fulton calls 7am to 7pm.
How do I reset an AC that is not cooling?
Resetting an AC means checking power and controls in order. The first list clears the simple causes. Anything past it needs a technician with meters and gauges.
What you can check
- Thermostat on Cool, below room temperature, fan Auto.
- Air filter: hold it to light; replace if gray.
- Breakers and outdoor disconnect: reset once, never twice.
- Leaves, grass or a fence crowding the outdoor unit.
What a technician checks
- Refrigerant charge measured, leaks found and repaired.
- Capacitor and contactor tested at the outdoor unit.
- Indoor coil and blower checked for dirt and ice.
- Condensate drain cleared and float switch tested.
Why won't my house cool below 75 degrees?
ASHRAE's 1 percent design day for Atlanta is 91.6F with a 73.6F wet bulb. On afternoons like that, a right-sized system in a South Fulton home may run nonstop, especially with ductwork or the air handler up in a hot attic. Running all afternoon isn't a fault by itself.
So a South Fulton house stuck at 75 at 4pm in July can be normal if it catches up by evening. Never below 75, even overnight? Suspect airflow, a dirty coil or a leak.