Diagnosing Compressor Motor
The compressor motors for refrigeration and air conditioning are simple to
diagnose, but they can be frustrating if you are unfamiliar with them. It's
possible that the compressor motor windings gets exact voltages and has a
strong capacitor but won't run or trips the circuit breaker. In such situation,
your troubleshooting experience would be extremely useful. Important
information and points about compressor motor troubleshooting are given below.
There are only 3 motor winding failures:
1. Open Winding – This is when one of the wires that make up the motor
windings is broken or separated. If this happens, there will be pairs of
terminal pins that will read at zero ohms.
2. Shorted Winding – If the insulation on the windings has failed, sometimes
one part of the winding is making electrical contact with another part of the
winding. If this happens, some pairs of terminal pins will have similar
resistance reading.
3. Grounded Winding – This is similar to the shorted winding but the wire
with the broken insulation is making electrical contact with the compressor
casing or ground. In other words, any terminal pins paired with the
compressor casing that has ohmmeter reading is considered grounded.
Here are the important points to remember in interpreting the test result:
•
The compressor is shorted if; some pairs of terminal pins will have similar
resistance reading.
•
The compressor is open if; there will be pair/s of terminal pins that will read
at zero ohms.
•
The compressor is grounded if; any terminal pins paired with the compressor
will have resistance reading.
BASIC COMPRESSOR WIRING (PSC)