AC Not Blowing Cold Air? 9 Causes and What to Do First
Few things are more frustrating than an air conditioner that hums along all afternoon while the house stays at 82 degrees. If your AC is not blowing cold air, work through these causes in order. The first three you can check yourself; the rest need an AC repair technician.
1. Dirty air filter
A clogged filter starves the evaporator coil of airflow. The coil gets too cold, ices over, and the air passing through is barely cooled. Pull the filter; if you cannot see light through it, replace it and shut the system off for two hours to thaw the coil.
2. Thermostat set wrong
Make sure it says COOL, not HEAT or FAN ON. With the fan set to ON the blower runs constantly and blows room-temperature air between cooling cycles, which feels like the AC is not working.
3. Tripped breaker or blown disconnect fuse
The outdoor unit has its own breaker and often a fused disconnect on the wall next to it. If the indoor blower runs but the outdoor fan is silent, check both.
4. Frozen evaporator coil
Ice on the copper line or a block of frost on the indoor coil means either restricted airflow or low refrigerant. Shut the system off, let it thaw, and call. Running a frozen AC can destroy the compressor.
5. Failed capacitor
The single most common summer AC repair. The outdoor fan or compressor hums but will not start. This is a quick, inexpensive fix when caught early; left alone it burns out the compressor.
6. Refrigerant leak
Air conditioners do not "use up" refrigerant. If it is low, it leaked. A proper repair finds and fixes the leak, then recharges the system to the manufacturer's specification.
7. Dirty condenser coil
In Minnesota, June cottonwood season packs the outdoor coil with fluff. The unit cannot reject heat, pressures climb, and cooling drops. A spring AC tune-up prevents this.
8. Failed contactor or fan motor
If the outdoor unit is silent while the thermostat calls for cooling, the contactor or fan motor may be gone.
9. Compressor failure
The worst case. On systems over 12 years old, especially R-22 units, we will show you the replacement numbers next to the repair.
When to call
If the filter is clean, the thermostat is right and the breaker is on, stop troubleshooting and call. Same-day AC repair is available across Minnesota, including Minneapolis, Saint Paul, Rochester, Duluth and St. Cloud.