The most common types o f compressors encountered when servicing residential and light commercial equipment are the reciprocating, rotary, and scroll-type hermetic compressors. In a hermetic compressor (Figure SP-9-1) the motor is connected directly to the compressor crankshaft. Both components are sealed in a welded steel enclosure or shell. Because it is sealed, the entire unit must be replaced when it fails.
The semi-hermetic compressor (Figure SP-9-T), also called a serviceable hermetic compressor, is used in commercial equipment. In the semi-hermetic compressor, the compressor motor is connected directly to the compressor crankshaft. If failure occurs, access to the compressor or motor for some repairs is possible by removal of the cylinder heads and/or bottom and end plates.
Because the majority o f compressors used in residential and light commercial equipment are hermetic compressors, the remainder o f this section will emphasize procedures used to service these compressors. Most of these same procedures can also be used when servicing semi-hermetic compressors.
