COMPRESSOR ELECTRICAL DIAGNOSTICS
The compressor does not start or will trip repeatedly on overload.
CHECK RESISTANCE (OHM) VALUES
NOTE: Compressor windings can have very low ohm values. Use a properly calibrated meter.
Perform the resistance test after the compressor cools. The compressor dome should be cool enough to touch (below 120°F/49°C) to assure that the overload is closed and the resistance readings will be accurate.
SINGLE PHASE COMPRESSORS
1.Disconnect power from the condensing unit and remove the wires from the compressor terminals.
2.The resistance values between C and S and between C and R, when added together should equal the resistance value between S and R.
3.If the overload is open, there will be a resistance reading between S and R, and open readings between C and S and between C and R. Allow the compressor to cool, then check the readings again.
CHECK MOTOR WINDINGS TO GROUND
Check continuity between all three terminals and the compressor shell or copper refrigeration line. Scrape metal surface to get good contact. If continuity is present, the compressor windings are grounded and the compressor should be replaced.
To determine if the Compressor is seized check the amp draw while the compressor is trying to start.
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