Compressor Checks - Friedrich Kuhl KCS12B10A Service Manual

Compressor Checks

WARNING
ELECTRIC SHOCK HAZARD
Turn off electric power before service or
installation.
All electrical connections and wiring MUST be
the National Electrical Code and all local codes
which have jurisdiction.
Failure to do so can result in personal injury or
death.
Single Phase Running and L.R.A. Test
NOTE: The L.R.A. can be found on the rating plate.
Select the proper amperage scale and clamp the meter probe around the wire to the "C" terminal of the compressor.
Turn on the unit and read the running amperage on the meter. If the compressor does not start, the reading will indicate the locked rotor amperage
(L.R.A.).
Overloads
The compressor is equipped with either an external or internal overload which senses both motor amperage and winding temperature. High motor
temperature or amperage heats the overload causing it to open, breaking the common circuit within the compressor. Heat generated within the
compressor shell, usually due to recycling of the motor, is slow to dissipate. It may take anywhere from a few minutes to several hours for the
overload to reset.
Checking the Overloads
CAUTION: Before attempting to check overloads, ensure that compressor is cool to touch.
External Overloads
With power off, remove the leads from compressor terminals. If the compressor is hot, allow the overload to cool before starting check. Using an
ohmmeter, test continuity across the terminals of the external overload. If you do not have continuity; this indicates that the overload is open and must
be replaced.
Internal Overloads
Some model compressors are equipped with an internal overload. The overload is embedded in the motor windings to sense the winding temperature
and/or current draw. The overload is connected in series with the common motor terminal.
Should the internal temperature and/or current draw become excessive, the contacts in the overload will open, turning off the compressor. The
overload will automatically reset, but may require several hours before the heat is dissipated.
Checking the Internal Overload
1. With no power to unit, remove the leads from the compressor terminals.
2. Using an ohmmeter, test continuity between terminals C-S and C-R. If no continuity, and the compressor is not hot to the touch, the
compressor overload is open, and the compressor should be replaced.
68
COMPONENT TESTING
WARNING
BURN HAZARD
Proper safety procedures must be followed,
and proper protective clothing must be worn
when working with a torch.
Failure to follow these procedures could
result in moderate or serious injury.