What to Consider When Buying an Air Conditioner Compressor

An AC unit.

An air conditioner compressor provides cooled air by compressing low volume gas in to a high pressure and temperate gas. These compressors can leak or break, causing your entire air conditioning system to be useless. If you need to replace your compressor, here are a few things to look for.

Scroll, Screw, or Piston Compressor

Depending on the type of air conditioner system you have, you may not have a choice in this. If you can choose, here are a few things to keep in mind about the different types of compressors.


A scroll compressor is a more popular choice for air conditioning compressors. They tend to leak less than the other types and are typically more energy efficient in the way they operate. A scroll compressor is designed to move the refrigerant gas in a continuous flow. This helps to keep the system quieter, which most people prefer. Many companies will warranty the scroll compressors for a longer period of time than the other types. They may be a little more expensive, but if you want a low maintenance and quiet system, it may be worth the extra money.


Screw compressors are another popular choice. They use a simple design that can be repaired easily if needed. The design is comprised of two screw-shaped rotors that will spin in opposite directions. They are almost as quiet as the scroll compressors, although you can expect a little more noise. While the screw air conditioner compressor is efficient, it's not as efficient as the scroll version. If you are wanting a compressor that is relatively quiet, easy to work on, and less expensive, this may be the best choice.


A piston compressor is the least popular type of air conditioner compressor available. These are found in many older systems and are still available as replacements though. The piston creates more noise than the other two compressors. The design requires motor-driven piston action to compress the refrigerant gas. Not only are these systems louder, but they also tend to be less efficient than others since they do not supply a steady flow of gas through the system. Today, these are more commonly seen in large, high-pressure systems, like those found in warehouses and large retail buildings.

Energy Star Rating

All home appliances, including the major parts to fix them, can be found with an Energy Star rating. In order to qualify for an Energy Star rating, the compressor must be at least 20% more efficient than current federal standards. Air conditioners and the parts will carry a SEER (seasonal energy efficiency rating) rating. A SEER rating of higher than 12 is what you should be looking for. You may pay more out of pocket for this part in the beginning, but the energy saved will pay back that investment in just a few years.