Incorrectly tensioned accessory drive belts may cause noise when the A/C compressor clutch is engaged, which may be confused with an A/C compressor noise, and a slight noise when the A/C compressor clutch is disengaged (or lack thereof). The noise from the drive belts depends on the frequency of their rotation. Therefore, depending on the belt tension at different engine speeds, the drive belts can make strange noises that are often mistaken for the sounds of a failed compressor.
Adjustment
1. Choose a quiet place to test. Repeat as completely as possible the conditions for the occurrence of extraneous noise. To clearly distinguish the sound of a running compressor, turn it on and off several times. To reproduce high altitude conditions, limit the air flow through the condenser. Install a gauge manifold assembly to monitor the discharge pressure, which must not exceed 2070 kPa.
2. Tighten all the compressor mounting bolts, the A/C compressor clutch mounting bolt and adjust the tension of the compressor drive belt. Check the reliability of the installation of the winding of the electromagnetic clutch (no rotation or wobble).
3. Check that there is no contact or friction between the air conditioning hoses and adjacent parts, which can cause extraneous noise.
4. Check the coolant level.
5. Listen again to the sound of the compressor running.
6. If the noise remains, then loosen the compressor mounting bolts and re-tighten them.
7. If extraneous noise remains, then replace the compressor and repeat the test.