Compressor Troubleshooting; Compressor Failures; Mechanical Failures - Bryant Base Series Application Manual And Service Manual

Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual
3. Expose the sensor holder
4. Slide out the sensor, slide in replacement and reinstall the cover
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.

COMPRESSOR TROUBLESHOOTING

Compressor Failures

Compressor failures are classified in 2 broad failure categories;
mechanical and electrical. Both types are discussed below.

Mechanical Failures

A compressor is a mechanical pump driven by an electric motor
contained in a welded or hermetic shell. In a mechanical failure, motor
or electrical circuit appears normal, but compressor does not function
normally.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Do not supply power to unit with compressor terminal box cover
removed.
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ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Exercise extreme caution when reading compressor currents when
high-voltage power is on. Correct any of the problems described below
before installing and running a replacement compressor.
Locked Rotor
In this type of failure, compressor motor and all starting components are
normal. When compressor attempts to start, it draws locked rotor current
and cycles off on internal protection. Locked rotor current is measured
by applying a clamp-on ammeter around common (blk) lead of
compressor. Current drawn when it attempts to start is then measured.
Locked rotor amp (LRA) value is stamped on compressor nameplate.
If compressor draws locked rotor amps and all other external sources of
problems have been eliminated, compressor must be replaced. Because
compressor is a sealed unit, it is impossible to determine exact
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mechanical failure. However, complete system should be checked for
abnormalities such as incorrect refrigerant charge, restrictions,
insufficient airflow across indoor or outdoor coil, etc., which could be
contributing to the failure.
Runs, Does Not Pump
In this type of failure, compressor motor runs and turns compressor, but
compressor does not pump refrigerant. A clamp-on ampmeter on
common leg shows a very low current draw, much lower than rated load
amp (RLA) value stamped on compressor nameplate. Because no
refrigerant is being pumped, there is no return gas to cool compressor
motor. It eventually overheats and shuts off on its internal protection.
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WARNING
!
WARNING
!