Signs Of AC Compressor Motor Failure

12 May 2016
 Categories: , Articles


Your central air conditioning system has a great deal of moving parts that need to work together to cool your home. One of the most important parts is the compressor motor, and some fairly in-depth repairs will need to be completed if the motor goes bad. You will need to speak with a heating and air conditioning professional about the repairs, but you will first need to understand some of the signs that the compressor motor is going bad.

Poor AC Cooling Performance

The compressor is the electrical pump that sits in the outdoor condenser part of the air conditioning system. This pump is responsible for compressing refrigerant so high-pressure coolant can be moved through the system. When the coolant is placed under high pressure, it turns into a fluid. The fluid moves through the coolant lines that attach to your home and it pulls heat out of the air. Cooled air can then move to the vents.

The entire air cooling process is dependent on whether or not the coolant can pull heat out of the air. The refrigerant must be in liquid form to do this, and this means that the compressor must be working properly. When the compressor starts to fail, the coolant may remain in vapor form or it may become a lower pressure fluid. The coolant will not be able to pull as much heat out of the air. The result will be lukewarm or barely cool air moving through your vents.

If the compressor pump is unable to pressurize the fluid properly, then you may also notice that your AC system turns on more frequently in an attempt to cool your home. You will likely see electric bills that are higher and notice a home that is not nearly as cool as it should be.

Noisy Condenser Unit

Your outdoor condenser will make some noise as the fan and the compressor pump work. However, you should not hear any grinding or rumbling sounds coming from the unit. This is a sign that the compressor pump is starting to break. The pump utilizes a crankshaft and a piston to compress coolant. When the pump accepts low pressure coolant, the piston will be in the low position. This allows the coolant to move into the cylinder that sits above the piston. The piston then moves upward to squeeze the coolant. A discharge valve then opens along the top of the cylinder and the high-pressure coolant moves out of the chamber.

The compression process requires the movement of the crankshaft, the piston, and the metal rod that connects these two components together. If one of the moving parts starts to wear down, then you will hear some noise as the worn part moves. In some cases, the condenser may start to vibrate as well. Also, the piston will have rubber rings on the top. These rings help to seal the chamber inside the pump so coolant cannot move down and around the piston. The rubber will wear away over time and get stuck around the piston. This can create some grinding noises as the piston moves.

If you notice the signs of a poor compressor pump, then it is wise to contact an HVAC professional as soon as possible. The compressor can sometimes be rebuilt, especially if seals and rings are broken and need replacement. However, the pump is likely to break beyond repair if you allow it to run too long with a broken part or piece. If the compressor pump does need to be replaced completely, then you can ask your HVAC technician to replace the pump with a refurbished one. This will help to reduce the costs of replacing an expensive component of the AC system.