Blackstone Mechanical Contractors

Preventable Causes of Compressor Failure

Monday, January 30, 2017


There are many things that can cause a failure of your HVAC system. Fortunately, many fixes are easily identifiable and relatively inexpensive. Some examples of this type of fix can be loose wiring or improperly maintained air filters. Most HVAC systems that are properly installed, correctly started up and are well maintained are designed to last about 15 years. The life of the system can be severely shortened if routine maintenance is not followed. This is especially true when it comes to your compressor.


The compressor is an essential component and is the “heartbeat” of the system because it pumps the refrigerant (vapor) through the coils and line-set. Without the compressor there would be no transfer of heat and no relief from rising temperatures. The compressor “squeezes” the refrigerant into a smaller space, producing gas under high pressure and high temperature. The gas flows through the condensing coil, the heat transfer is by means of an air cooled or water cooled process.



You may hear about several kinds of compressors. The most common types are:

  •      -Reciprocating: similar to an automobile engine the piston works to compress the refrigerant in a straight line back and forth motion. There can be multi-cylinder compressors. 
  •      -Scroll: a scroll compressor has one fixed scroll and another orbiting scroll that rotates. As it rotates it pushes refrigerant to the center and through to the condenser. The scroll compressor has fewer moving parts and is a smoother and quieter process.  
  •      -Screw: The screw compressor traps the gas as helical rotors revolve in the cylinder. This is usually in use in 20-ton or above machines.
  •      -Rotary: As the blade rotates, trapped vapor in the space ahead of the blade is compressed into high pressure gas after which it is discharged to the condenser through the exhaust port. The number of blades can range from two to eight in a single system
  •      -Centrifugal: at the heart of the system is the impeller. The impeller achieves pressure rise by adding energy to a continuous flow of fluid through the rotor or impellor assembly.


Compressors can fail for many reasons: wear and tear, age, improper installation or repairs, poor maintenance practices, power surge and others. The most common causes of compressor failure follow:

  •      -Dirty Outdoor (Condenser) Coils: This is the number one preventable cause of compressor failure. When dust, grime, dirt and scales build up on the condenser coil, the heat transfer is limited. The compressor has to continuously cycle trying to eject the heat. The increased pressure and temperature causes the compressor to overheat and can ultimately fail.
  •      -Dirty Filters/Indoor (Evaporator) Coils: If the air flow across the evaporator becomes blocked or restricted then the suction (low side) pressure will drop causing the refrigerant lines and coil to ice up. When this occurs, liquid refrigerant can then return to the compressor (vapor pump) damaging the internal components by displacing the refrigerant oil or breaking the valves.
  •      -Low Refrigerant Charge: Obviously, when there is a leak in your system, the refrigerant level will drop. The level will drop so low that the compressor has to work too hard to pump enough refrigerant through the system to adequately cool the space and avoid icing up. This causes strain to the compressor by running higher temperatures internally to cool the compressor motor which could lead to premature failure.
  •      -Too Much Refrigerant: Conversely, too much refrigerant or the wrong type of refrigerant, will also put strain on the compressor from increased operating pressures and temperatures.
  •      -Electrical Problems: An electrical failure of the motor in the compressors can cause a build-up of acids in the system which can cause damage to the other parts in addition to the compressor. Damaged or worn wires, terminals, fuses or bad connectors can cause electrical failures.


This is a short list of issues to watch in your commercial HVAC system focusing on the importance of the compressor. We can help you mitigate this risk and expense through our experience and expertise. We are different from many companies in that we are focused on all aspects of HVAC from the concept to completion and can help your project with installation, start-up and preventative maintenance.


W.O. Blackstone offers a full range of professional mechanical contracting services for clients in the commercial office, healthcare, institutional and industrial markets in South Carolina, North Carolina, and Georgia.

Since 1937, W.O. Blackstone has been about the business of helping building owners, general contractors, property managers and design engineers provide effective solutions for HVAC and Plumbing systems and Industrial Process Piping.. For more information, please visit or contact us at (803) 252-8222.

W.O. Blackstone Mechanical Contractors