Car is a 1995 S320, A/C blow cold air. But the compressor would not turn back on when turn off on short trip. It would always work if car stop over long period or overnight.

Jack

Is your auxilarry fan working ? Does the compressor cut-off and not start while you are driving ? Does it happen when idling ? or this only happens after a stop ?

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Saumil S. Patel

Check if your a/c relay is working.

It only happens after short stop. Aux fans work...Where is the relay.

Jack

I am not familiar with this car, but your problem seems to be related to coolant temperature. When you start the car after a brief stop, do you notice that your engine temp has gone higher than what it was before stopping ? Will the a/c come on after the car has run for a while and the engine temp has dropped ?

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Saumil S. Patel

The compressor would re-start on short stop, but not always.

Jack

On your car, does the aux fan stay on after the car is turned off. If not (as in my 87, 260E), the engine temp rises substantially after the car has been turned off. On my car, this would cause the activation of the coolant temp switch which cuts off the compressor. I am thinking, your car may be similar, so the compressor cuts off due to high engine temp after stoppage, but this temp has to be real high to cut-off the compressor and should not cut-off the compressor once the car begins to run and the engine temp has come back down again. So if such a temp switch is in your car, it is a bad switch, I would replace it and see if it fixes the problem.

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Saumil S. Patel

Check for belt slippage. If your belt slips, it will trigger the AC speed sensor and cause your compressor to shut off. More likely to slip when engine is hot.

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Thats correct, if there is a substantial difference between the compressor pulley rpm and the engine rpm, the compressor will cut off. The Klima relay thinks that the compressor has siezed. This function is built into the Klima relay to protect the belt. But for this to occur, the belt has to be very loose or slip substantially.

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Saumil S. Patel