The compressor inside your air conditioning (AC) unit is arguably the hardest working part of your home cooling system. Here’s a quick guide to your AC compressor and how to keep the important part running smoothly.


When your AC system cycles on, refrigerant gas flows into the AC compressor, which compresses the gas. The compression of the gas heats the refrigerant. Then, the refrigerant flows into the condenser to start cooling your home.

Compressors are designed to press against the refrigerant gas and reduce its volume. Most home AC systems in the recent past came with reciprocating compressors. As many as eight pistons pump up and down inside the AC compressor cylinders to compress the refrigerant gas.

Reciprocating compressors are efficient. However, reciprocating compressors have a lot of moving parts.

Scroll-type AC compressors compress refrigerant gas in a different way. A fixed scroll (coil) is in the center of the compressor. A second outer scroll rotates around the inner scroll. The refrigerant gas that enters the unit is compressed in the center of the scroll-type compressor by the rotating action rather than by pumping movement.

Because the scroll-type compressors require fewer moving parts than reciprocating AC compressors, the scroll-type compressors have become more popular. Fewer parts in the scroll-type compressors make them less likely to break down or need service.

Other AC compressor types include screw-type, rotary, and centrifugal compressors. Screw-type, rotary, and centrifugal compressors are most often on heating, air conditioning, and ventilation (HVAC) systems for large commercial, medical, and industrial buildings.


AC systems cool your home and remove summer humidity from the air. As compressed refrigerant gas leaves the AC compressor, heat releases through the evaporative coils. Moisture from the air and the AC operation are both removed when the compressor and condenser run.

Single-stage compressors only remain running as long as it takes to cool your home. If your home only requires a small amount of cooling, your AC system’s compressor may not run long enough to remove enough moisture from the air.

Modern residential AC compressors are available in standard single-stage compressors, but more homeowners choose to install AC units with two-stage or variable-capacity compressors. Both two-stage and variable-capacity compressors help eliminate the problem of too-short compressor cycles and inadequate dehumidification.

The two-stage compressor can run at the standard rate or at a second, lower cooling temperature. The second-stage option lets the AC compressor run for longer periods. The increased compressor operation periods ensure that the correct amount of moisture is removed by a two-stage AC system. In most cases, a two-stage AC compressor is more energy-efficient than a single-stage AC compressor.

Variable-capacity compressors offer the most customization of home cooling and humidity control. The variable-capacity AC compressor self-modulates throughout the day to respond to the indoor temperature. When less cooling is needed inside your home, the variable-capacity compressor goes into efficiency mode all on its own.

The variable-capacity AC compressor effectively removes excess humidity from your home, since the variable-phase compressor runs for longer periods during times when less cooling is needed. The variable-capacity AC compressor doesn’t start and stop for brief periods like a single-stage AC compressor does.


Your AC compressor will last longer and offer more reliable service when your AC system has proper maintenance. Change your air filters as your HVAC repair professional recommends to keep debris, dust, and pollen out of your AC components.

Schedule annual maintenance of your AC system. Your HVAC pro performs a thorough check for any problems that could affect your AC compressor. Your HVAC professional tightens up electrical connections, checks the compressor motor, and fixes small problems with your AC system before your compressor is adversely affected.

Some of the issues that can affect your AC compressor include:

  • Too-high pressure of refrigerant
  • Too-low suction of refrigerant
  • Failed bearing in compressor
  • Inadequate airflow around coils

Don’t allow vegetation to clog the area around your exterior AC unit. Remove weeds and debris from all sides of the exterior AC unit so air circulates freely around the evaporator and condenser coils.

AC compressors are very sensitive to variations in electrical voltage. If your home has fluctuations in line voltage, expect a shorter useful life for your AC compressor. Too-low voltage makes the AC compressor motor draw excess current, which can lead to an overheated compressor motor. Too-high voltage can lead to motor failure over time.

Your HVAC professional has tools to check for refrigerant leaks, voltage issues, and other problems that may plague your AC compressor. Rely on the experts’ knowledge and skills to keep your AC compressor in top running order this summer.

Take care of your AC compressor this summer in the Seattle, Washington, area by contacting AirGanic Seattle today. We install new AC systems and service existing AC systems for optimal AC compressor performance.

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