Air conditioners (ACs) don't work well when the temperatures are freezing. In fact, they are meant to operate at temperatures above 60 degrees Fahrenheit, and your AC may suffer damage if you run it at extremely low temperatures. Here are some of the damages associated with cold-weather AC operation:
The Cooling Oil Thickens
The compressor's main job is to circulate the refrigerant throughout the AC system. Proper refrigerant circulation is necessary for efficient heat exchange. Just like many other electromechanical systems, the compressor generates heat when it is running and that heat may compromise its operation. The heat is channeled away from the compressor by oil that is just thick enough to circulate freely. The oil also lubricates the moving parts of the compressor.
When the temperatures fall dangerously low, the oil thickens and becomes unable to circulate freely. The compressor then becomes unable to get rid of the heat it generates. At the same time, the friction between the moving parts of the compressor can also become unbearable. This can cause catastrophic compressor failure that is costly to rectify.
The coils, which carry refrigerant, are also meant to operate within a given temperature range. This ensures that the refrigerant always remains at the gaseous state. When temperatures fall too low, the refrigerant may liquefy and enter the compressor in the wrong state (liquid). This not only interferes with the AC's efficiency, but it can also cause compressor damage when the heat exchange operation of the AC fails.
Running the AC when the temperatures are too low can also lead to condensation and drainage issues. This happens when moisture laden air meets the cold parts of the AC (such as the cooling element inside the unit) and sheds their moisture in the form of condensation. This moisture usually drains through the derail lines and collects in the pan, but it may fail to drain if the temperature is very low and the coils are frozen over. This can cause damage to the unit if left unattended.
As you can see, the AC isn't meant for heating your house when it gets cold; in fact, that is what the heater is for. In fact, it's for this reason that newer AC models are equipped with sensors that prevent the AC from running when temperatures fall below a preset level. Consult a technician for professional service in case your AC suffers weather related damage. You can also look at HVAC reviews to see what kinds of temperatures are problematic for your system.