A/C Compressor Noise

Noises that develop during air-conditioning operation 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. Improper belt tension is also often the source of an objectionable noise and can easily be mistaken for internal compressor troubles.

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 within the compressor. See Compressor Noise Test.

ADJUSTMENT PROCEDURES
1. Select a quiet area for testing. Switch compressor on and off several times to clearly identify compressor noise.
2. Tighten all compressor mounting bolts, clutch mounting bolt, and compressor drive belts. Check that plumbing is not rubbing other parts.
3. Make sure that drive bolts are equally tensioned. Replace any parts that are defective or missing.
4. Retest vehicle; if noise persists, continue trouble shooting system for source of noise.