The compressor is the starting point for the cooling system in a central air conditioning unit. Gas refrigerant, which acts as the system's fuel, is pumped into action by the compressor. The gas refrigerant at the end of the cooling cycle then ends up back at the compressor to be reused. So a compressor failure means your cooling system is going to stop working.
What causes a compressor to shut down? Here are a few of the potential causes, but most of the fixes will require a call to your trusted air conditioning repair person.
The outdoor portion of your central air conditioner is called the condensing unit. This unit contains the compressor, condenser coils, and a motorized fan inside a grated case. Gas pushed out by the compressor enters the condenser coils, which turn the gas into liquid. That phase change makes the coils hot but that heat is supposed to be offset by the fan and the ventilation provided by the case.
But problems inside the condensing unit can lead to overheated conditions, which can shut down the compressor.
There are a variety of problems that can lead to overheating. Improper ventilation caused by grate blockages is one of the easiest to diagnose with a visual inspection. But problems such as faulty compressor wiring, malfunctioning condenser coils, or a burned out fan motor are best left to a professional.
Low or Improper Refrigerant
The compressor exists to put out and accept enough refrigerant gas to power the system. Low levels of refrigerant can lead to the fuel running out before it makes it through the system and back to the compressor. Since the compressor has nothing to output, it simply stops running.
Improper refrigerant can also lead to a compressor shutdown. There are different types of refrigerant on the market but not all are safe to use in your specific unit. If someone loaded the wrong refrigerant into the system, the fuel won't make it through the system and back to the compressor.
Refrigerant is a hazardous chemical best left to professional HVAC technicians from places like Advanced Heating & Cooling. Don't try to check or change the refrigerant on your own.
Dirty condenser coils can become as problematic as broken or otherwise malfunctioning coils. Changes to the surface of the coils can impact the important chemical reaction of the gas refrigerant and the required external cooling.
There are two different ways dirty coils can shut down the compressor. First, the coils can be so dirty not enough refrigerant makes it through the cooling system, which means not enough – or none at all – will return to the compressor. Or the dirty coils can become overly hot even with proper ventilation and the fan. This can lead to an overheating situation that can shut down the compressor.