I remember someone mentioned that in his case, the problem was with the speed sensor (either engine or compressor, I dont remember) but the strange part was that the compressor would come on without a restart, and I was puzzled, but what I am trying to say is that just because the compressor comes on without a restart would not rule out the speed mismatch based cut-off condition. Atleast check the connections to the speed sensors, make sure they are clean. The compressor speed sensor should produce an a/c voltage, on my 87, 260E compressor (assuming the compressor is similar in our cars), about 0.3V at idle.

The pressures are not that high right before the cut-off, your pressure cut-off switch could be malfunctioning. Try bypassing that switch, just jumper the two wires.

The fact that you can make it work with a higher rpm I think rules out the coolant temperature sensor based cut-off, because the temperature is not going to change instantaneously when you change RPM. I am assuming you have sufficient coolant in the system.

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Saumil S. Patel