Refrigerator Open Windings Compressor Testing

Place a test probe on terminal one. With the other probe touch terminal two. The meter needle should deflect. This shows there is a circuit. Repeat the procedure until the circuitry between the terminals is confirmed. There should be a reading across each pair of terminals.

The windings in a three-phase compressor are different than a single-phase compressor. In the three-phase compressor, you should read the same amount of resistance through the three windings. This is not true in the single-phase compressors. The reason is that the start-winding has more wiring turns in order to develop more torque on start up. The run-winding has a heavier gauge wire with fewer turns, thus the resistance readings will be different between the three windings. Knowing this, it is possible to identify the windings in a single-phase compressor.

RUN—The lowest reading of resistance—(about one ohm)
START—The middle reading of resistance—(about five to 22 ohms)
COMMON—The maximum resistance reading—(total of all windings)

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