Hi Chris,

In my experience if the clutch is going, it either doesn't engage at all or it makes a lot of noise. Chattering if it's slipping or an ear piercing squealing sound if the clutch bearing is dry.

If the performance has dropped it means you've either loss the proper charge of refrigerant or your compressor is not compressing it.

I have a had a recurring problem with the unit on my 98 S90 blowing off refrigerant (high pressure relief valve tripping) on really hot days when the pressure exceeds the relief valves 538 psi tripping point. When this happens you will hear a loud, jet engine type of roar coming from the engine compartment for about 5-10 seconds and you will sometimes see white vapor coming from under the hood (if you are stopped at a traffic light). You won't see the vapor if the vehicle is moving. After this happens there is greatly diminished cooling but no unusual vibrations. Recharging the system brings back the cooling capacity.

You could....... try to recharge the system and see what happens. I doubt you can make things much worse by doing this if the compressor is already seriously damaged. You might get lucky for the cost of a R134a can. If it doesn't work, you know you are in for a system overhaul.

Good luck.

DEWFPO
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1998 S90 083,228 and 1995 964 154,100