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In a recent TSB from GM, it was stated that 60% of the compressors returned to GM for excessive noise were not defective. We suggest that you check the following items before deciding that the compressor is bad: 1. Check all the accessory brackets for cracks, missing bolts or nuts. Any vibration can cause excessive noise. Pry gently against the brackets to see if the noise changes pitch. If it does, the noise is not the compressor. 2. Check the hoses to see if they are transferring the engine vibration back to the passenger compartment, causing the noise. Gently apply pressure to the hoses one at a time to see if the noise changes. 3. Check all drive belts, idlers, and tensioners for excessive movement. The extra movement can be caused by worn parts, which create the excessive noise. 4. Excessive high side pressure can cause abnormal compressor noise. We have found that due to the placement of the high side access port, the true high side reading may not be shown on the gauge. If the access port is after the restriction, the true pressure can be much greater. Checking the temperature of the condenser will help to diagnose this problem. 5. An overcharge of refrigerant, or charging with contaminated refrigerant will cause high head pressures, causing excessive noise. Refrigerants that contain excessive levels of "NON?CONDENSABLE GASES" will cause noise also. 6. Insufficient airflow across
the condenser will cause excessive high side pressure, which
might cause compressor noise. Be sure that whatever method used
to cool the condenser (fan clutch or radiator fan motor) is in
proper working order, and is moving the proper amount of air
through the condenser. Any foreign material blocking airflow
through the condenser cooling coils will also cause increased
high side pressure. |
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