A/C Compressor - Noise Replacement Criteria

Bulletin No. 012/95

Issued 11/06/95

Revised

Category U

Applicable Model/s: See Below

Subject: A/C COMPRESSOR NOISE REPLACEMENT CRITERIA

APPLICABLE MODELS/VINS
1990 - 94 323 / Protege Vehicles
1992 - 96 MX-3 Vehicles
1993 - 96 626 / MX-6 Vehicles


DESCRIPTION

If a customer complains of compressor noise or compressor noise is present after an A/C repair, follow the instructions in this bulletin to determine the cause prior to replacing the compressor.

NOTE: The instructions in this bulletin are only for the models listed above. Refer to the workshop manual for diagnosing all other models.

PREVENTING COMPRESSOR NOISE AFTER AN A/C REPAIR

To prevent noise from occurring after A/C component replacement (i.e. condenser, compressor, evaporator, receiver dryer pipes and hoses) technicians must add the "proper type" and the "correct amount" of refrigerant oil at the time of the repair.

USE THE TABLE BELOW TO DETERMINE BOTH TYPE AND AMOUNT OF REFRIGERANT.

REFRIGERANT OIL REPLACEMENT AMOUNTS AND REFRIGERANT OIL PART NUMBERS

PROCEDURES FOR MEASURING REFRIGERANT OIL WHEN REPLACING THE COMPRESSOR

1. Remove and record the amount of refrigerant oil in the old compressor.

2. Add 15 - 20cc (0.5 - 0.6oz) of oil to the number recorded in step 1. NOTE: This sum represents the amount of new oil needed for the new compressor.

3. Drain the oil from the new compressor into a separate container.

4. Fill the new compressor with the amount of oil determined in step 2. Use the oil drained from the new compressor.

DIAGNOSING COMPRESSOR NOISE

Compressor noise can be caused by the following items.

^ Extremely High Head Pressure

^ Overcharged A/C System

^ Plugged Receiver Drier

^ Malfunctioning Expansion Valve


Perform steps 1 and 2 below prior to replacing any A/C related parts.

1. Install a manifold gauge according to the workshop manual and perform a performance test.

2. Record high and low side readings and compare to tables in workshop manual.

^ If discrepancies are found, repair as needed.


REPAIR PROCEDURES FOR COMPRESSOR NOISE

1. Apply the parking brake and start the vehicle.

2. Run the engine at a constant 3,000 - 4,000 rpm and switch the A/C system ON and OFF intermittently.

^ If the noise is still present, turn the A/C off for approximately 1 - 2 minutes and repeat the process.

NOTE: This process it designed to free a possible sticking compressor "vane."

^ If the noise is still present, proceed to step 3.

3. Evacuate the system.

4. Charge the system (with the correct freon) through the high side.

NOTE: This process is designed to free a possible sticking compressor "reed" valve.

5. while charging the system, add an additional 40cc of the designated compressor oil (Mineral Oil for R-12 systems, PAG oil for R-134a systems).

^ If the noise is still present, replace the compressor.


WARRANTY INFORMATION

After removal, install shipping caps to prevent refrigerant oil spillage and contamination. Insert the compressor into the container used for shipping and store the part for future inspection.