Sinclair AMC-15A, Service Manual

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Basic test procedure
11 Basic test procedure
11.1 Defective compressor
Compressors are single phase, 115 or 120 volt, depending on the model unit. All compressor
motors are permanent split capacitor type using only a running capacitor across the start and run
terminal.
All compressors are internally spring mounted and externally mounted on rubber isolators.
11.1.1 Compressor wiring test
Remove compressor terminal box cover and disconnect wires from terminals. Using an ohmmeter,
check continuity across the following:
Terminal "C" and "S" - no continuity
- Open winding - replace compressor.
Terminal "C" and "R" - no continuity
- Open winding - replace compressor.
Terminal "R" and "S" - no continuity
- Open winding - replace compressor.
11.1.2 Ground test
Use an ohmmeter set on its highest scale. Touch one lead to the compressor body (clean point of
contact as a good connection is a must) and the other probe in turn to each compressor terminal
(see Figure 2.) If a reading is obtained, the compressor is grounded and must be replaced.
11.1.3 Checking the compressor efficiency
The reason for compressor inefficiency is normally due to broken or damaged suction and/or
discharge valves, reducing the ability of the compressor to pump refrigerant gas.
This condition can be checked as follows:
1. Install a piercing valve on the suction and discharge or liquid process tube.
2. Attach gauges to the high and low sides of the system.
3. Start the system and run a “cooling or heating performance test.”