Compressor Functionality

TM 10-4110-262-13&P

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5. Under these conditions, the sight glass must indicate a full charge.

6. If refrigerant is low, evacuate the system and charge and evacuated unit by weight WP 0031 00.

Compressor Functionality

This procedure will test the compressor piston reed condition, piston to cylinder clearance, piston and cylinder

condition, and compressor performance capability.

Preparations Before the Test

1. Ambient temperature must be above 60 F (15 C).

2. Install a calibrated manifold gauge assembly.

3. Check the refrigerant charge (correct if needed).

4. Check for low side restrictions - pressures must be normal or high on the suction side.

5. Perform low side pump down (WP 0031 00). If the system does not pass the low side pump down

procedure, repair before continuing.

Compressor Functionality

1. If the temperature is below 36F, initiate manual defrost cycle until defrost is terminated.

a. Press the manual defrost key.

b. The defrost cycle will continue until the evaporator coil temperature reaches 48 F (9 C).

2. After manual defrost cycle is completed, go to Step 4.

3. If the temperature is above 36 F, go to Step 4.

4. Operate the unit in cool and cover the condenser to build discharge pressure to 300 to 350 psig.

5. Close the compressor suction valve (keep condenser covered).

6. When low side pumps down to a 10-inch vacuum, read discharge pressure. It should read 200 psig or

more.

7. Open the compressor suction valve.

8. Uncover the condenser.

9. If pressure is below 200 psig, replace the compressor.

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