If the entire air conditioning system is looked at as a body, the compressor is best described as its heart. Its basic function is to pump refrigerant--the system's blood, here known primarily as Freon -- throughout its closed loop of pipes and tubes. However, the compressor provides added functions, including compression of the vapor refrigerant. This process raises the temperature of the vapor to above the outside ambient temperature, thereby letting the cooler outside air be forced through the system's condenser coils by the compressor. This heat exchange process leads to the refrigerant changing state from a vapor to a liquid, eventually making it so the now unheated air can be pumped back into the room, maintaining the air at the desired temperature.
Types Of A/C Compressors
Compressors come in many different types, but the two common to air conditioning units are the centrifugal compressor and the scroll compressor. Scroll compressing technology has been in use for a long time. In this setup, the compressor uses a pair of interleaved scrolls to compress, pressurize or pump liquids and gases. This design also boasts a superior capacity to handle liquids, enabling small amounts of dirt and liquid to pass through without damaging the compressor, while at the same time increasing reliability by eliminating stress on the motor. Scroll compressors are considered very efficient and used in examples such as Lennox's HS-22, which includes a double-row condenser coil. Centrifugal compressors are considered best suited to continuous-duty applications, such as cooling units, ventilation fans and air movers because they give a high airflow at an efficient level but can't achieve a high compression ratio, meaning they can't handle large variations in pressure. Centrifugal force drives the compression of the refrigerant, rendering these compressors ideal for larger refrigerant volumes and low-pressure differentials.
Replacing Or Repairing An A/C Compressor
Compressors are covered by a governing body called the American Society of Mechanical Engineers, or ASME. Ideally, compressors and their components are certified by the ASME and, in fact, it's illegal in some states to sell compressors or related parts that are not ASME-certified. Home improvement and plumbing supply stores will likely sell both industrial grade and residential-use compressor parts. Filters, hoses and separators are considered the most often purchased parts and are widely available. According to one site, the U.S. Census Bureau estimates between 2.5 million and 3 million residential furnaces or air conditioners fail annually. Work on an A/C compressor is recommended to be done by a professional service technician because of the intricacies of the device. The technician will test the compressor to make sure it needs replacing, identifying the correct model and capacity. The unit will then be shut down from the power source, and the refrigerant will be thoroughly drained from the unit and disposed of in an environmentally friendly fashion. The refrigerant lines will then be cut, and the old compressor will be completely removed. The new compressor will be put in place and soldered onto the existing refrigerant lines. Air will then be vacuumed out of the system completely before new refrigerant is added at the proper charge (including temperature, pressure and volume).
Who Makes Replacement A/C Compressors?
A thoroughly nonexhaustive list of companies making A/C compressors:
- American Products Inc.
- Atlas Copco
- Compressed Air Systems
- Curtis-Toledo Inc.
- Hanover Co.
- Nebraska Neumatics
- Norwalk Compressor Co.
- Thomas Products
- Titus Co.