Why Your AC Keeps Freezing Up (and Why Adding Refrigerant Is Usually the Wrong Fix)
A frozen AC coil looks dramatic, but it is only a symptom. Something is making the evaporator coil run colder than it should, and until that is fixed the ice will keep coming back. Here are the causes we find in Utah homes, in order of frequency.
1. Restricted airflow
Dirty filter, dirty evaporator coil, closed registers, collapsed ductwork or a failing blower motor. Less warm air moving across the coil means the coil temperature drops below freezing. Fix the airflow, fix the ice.
2. Low refrigerant
Low charge lowers the pressure and temperature in the evaporator. Yes, adding refrigerant will stop the freezing for a while. But refrigerant does not evaporate, so if it is low there is a leak, and the ice will return. Insist on a leak search.
3. Running the AC when it is cool outside
Below about 60°F outdoor temperature, most residential systems will freeze. Common on Utah spring and fall nights.
4. Stuck or failed expansion valve
The TXV meters refrigerant into the coil. A stuck valve starves the coil and it freezes.
What to do right now
Turn the system to Off, set the fan to On, and let the ice melt completely. Then check the filter. If it freezes again, call for air conditioning repair. Running a frozen system can flood the compressor with liquid refrigerant and destroy it, turning a modest repair into a compressor replacement.
Frozen AC in Utah? We provide same-day service in Midvale, South Jordan, Herriman and every other city in the state.