| Step | Expected Result/Action |
|---|---|
| 12. Check the compressor motor for grounded windings as follows: Set up the VOM/DMM to measure resistance on the R x 10,000 ohm scale. Connect one lead of the VOM/DMM to a good ground connection, such as the compressor body or compressor discharge/suction line (Figure SP-9-16). Poor electrical contact because of a coat of paint, layer of dirt, or corrosion can cause an inaccurate measurement and hide a grounded winding. Touch the other meter lead to each of the motor leads, one lead at a time, and observe the meter indication. | VOM/DMM indicates infinity or high resistance. If a resistance reading is indicated, it should not be less than 1,000 ohms per volt. For example, on a 230- volt motor, the resistance should not be less than 230,000 ohms (230 volts x 1,000 ohms/volt = 230,000). A high resistance indicates that the motor windings are not grounded. Proceed to step 13 (single-phase PSC/CSR compressor) or step 14 (three-phase compressor) to check motor windings for partially shorted windings. VOM/DMM indicates low or zero resistance, or a measurable resistance that is less than 1,000 ohms per volt. This may indicate that the motor windings are grounded. Before replacing the compressor, refer to the caution below. |
