Air Conditioner freeze ups cause an A/C to blow little to no air through the vents, and the air is usually warm.
There are three basic reasons for air conditioner freeze ups:
- Insufficient air flow
- Low Refrigerant charge
- Outdoor temperature
1) The two most common causes of insufficient air flow are dirty filters and under sized ducts. A dirty filter limits air flow which in turn allows the cooling coil’s temperature to drop below freezing. Replacing the filter, monthly, usually alleviates this problem. Under sized ducts will also cause the system to freeze because it also limits the amount of air flowing over the cooling coil. This results in lowering the coil temperature and allowing the humidity in the air to collect on the coil and freeze.
2) Low Refrigerant Charge. The refrigerant system teeters on a delicate balance. If the system is not charged correctly, the system will not function properly. This malfunction may result in the poor cooling output and/or freezing up. Only a qualified, certified service technician can properly test and charge a refrigerant system. Check your small high pressure line (should be hot) and low pressure line (should be cold, but not frozen).
3) Outdoor temperature. If temperatures are too low, the system will not operate properly, and freeze up may occur. The outdoor unit does not function well in temperatures below 60 degrees F. A special “ambient temperature” control must be installed to allow the unit to run properly in cool temperatures, or you may open your windows and save energy. If the A/C is set lower than 70 degrees F, special adapters are required to be installed.