Symptom Diagnostic Procedures

COMPRESSOR NOISE
When investigating an air conditioning related noise, you must first know the conditions when the noise occurs. These conditions are weather, vehicle speed, in gear or in neutral, engine temperature or any other special conditions. Noises that develop during air conditioning operations can often be misleading. For example: what sounds like a failed front bearing or connecting rod may be caused by loose bolts, nuts, mounting brackets or a loose clutch assembly. Check the accessory drive belt tension (power steering, generator or air pump). Improper accessory drive belt tension can cause a misleading noise when the compressor is engaged and little or no noise when the compressor is disengaged. Drive belts are speed sensitive. That is, at different engine speeds and depending upon belt tension, belts can develop unusual noises that are often mistaken for mechanical problems inside the compressor.

Adjustment Procedures
1. Select a quiet area for testing. Duplicate conditions as much as possible. Switch the compressor on and off several times to clearly identify the compressor noise.

To duplicate high ambient conditions (high head pressure), restrict air-flow through condenser. Install manifold gage set to make sure discharge pressure does not exceed 2,070 kPa (300 psi).

2. Tighten all compressor mounting bolts, clutch mounting bolt, and compressor drive belt. Check to assure clutch coil is tight (no rotation or wobble).
3. Check the refrigerant hoses for rubbing or interference that could cause abnormal noise.
4. Check the refrigerant amount. (Refer to "Charging the System. ")
5. Recheck the compressor noise by the same procedure as given in step 1.
6. If noise still exists, loosen the compressor mounting bolts and re-tighten to the specified torque. Repeat step 1.
7. If noise continues, replace the compressor and repeat step 1.