A compressor failure is one of the more expensive of common failures of air conditioning systems. I’ll describe in this article the causes and prevention of failures. First I’ll explain what job the compressor has in cooling your home.
The compressor is a device weighing about 100 to 150 lbs and is inside the outside air conditioner in the yard. It takes cool gas from the indoor coil and compresses it to a higher pressure in the outdoor coil. At this higher pressure the gas’ temperature is above that of the surrounding space allowing it to reject its heat. Inside of its welded steel shell is an electric motor close-coupled to a gas compressor. These components spend their working life in an environment of refrigerant gas, without oxygen and moisture, bathed in oil. The motor draws its power from terminals bonded to the side of the shell. It is the job of the Air Conditioner installer to provide this oxygen-free, moisture-free condition during installation.
If your tooth hurts, avoiding an appointment with the dentist is not a good plan. Likewise, if your air conditioner seems to perform less well than before, have it inspected.
High Operating Temperature – Probably the single biggest cause of failure is long term operation with a low refrigerant charge. The compressor is the last item in a long circuit (up to 100 feet) that is cooled by refrigerant gas. When your system’s refrigerant charge has partially leaked away the compressor’s operating temperature rises while the interior of the home continues to be cooled.. If the leak is slow, it may operate for years at this higher temperature.
Capacitor Failure – The compressor in residential equipment is dependent for operation on devices called capacitors. Capacitors can change their electrical value over time and this change is detected by a good program of maintenance.
Dirty Coils – Inside the home and outside are heat exchanger coils. Depending on the season, one is hot and one is cold. Fouling of these coils increases the compression ratio the compressor operates under. This causes it to use more power, operate more hours, and operate outside of its designed conditions.
This is not an exhaustive list but covers quite a few failures. If you are not mechanically inclined to address these yourself, annual maintenance by a professional is a proper step toward lower operating costs and longer life for your equipment.