Auto Air Conditioning & Heater Repair: Air condition causing over-heating, compressor failure, compressor clutch

Question
I have a slight problem....
Whenever I turn on my air conditioner, my truck (1988 C1500 5.7) starts to overheat slowly. After I turn it off, it cools down, but slowly. Can this be a sign of early compressor failure, or is it just the air condition compressor clutch, or do I need oil in the cooling system. I hear a low knocking sound coming from the compressor, but I am not sure if that is a problem. I took off the drive belt and engaged the clutch and found that the compressor was kinda hard to turn with it engaged. Can I solve this problem by just replacing the clutch?, I dont wanna evacuate the refrigerant. My guess is that when engaged the compressor slows the drive belt and slows the waterpump. Not sure if this is right. (There is a new belt, waterpump, and the tenseioner and fanclutch are good)

Matthew

Answer
You stated : " After I turn it off, it cools down, but
              slowly.

Question: Turn OFF WHAT ?. WHAT cools down ?.




You stated: "Do I need oil in the cooling system ?.

Question: Oil in cooling system ?. I do not understand this
         statement.



You stated: "Found that the compressor was kinda hard to
           turn with it engaged.

Answer: This is NORMAL.



If you hear a KNOCKING sound from the compressor and are POSITIVE that the noise IS from the compressor, You will need to replace the compressor.

Changing a compressor is NOT as simple as it appears, So I do NOT recommend you try it without knowing EXACTLY what you are doing and how to replace the CORRECT amount of refrigerant oil and refrigeratn.

If this vehicle has the ORIGINAL radiator in it and it is near or in excess of 100,000 miles, I STRONGLY suggest that you REPLACE the radiator witha NEW one.

I did NOT say to have your radiator FLUSHED, CLEANED and or RECONDITIONED, What I DID say was to REPLACE it with a NEW ONE.

I have learned over the years that radiators tend to fail internally when at normal operating temperature and the ONLY cure is to replace it with a NEW one.

When you buy a NEW one, Make SURE that you tell them you have A/C on the vehicle.

QUESTION: Why did you NOT replace the thermostat ?.



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