Hello,

My car is e34 525 m20 '88.
When I drive and switch A/C on I notice an increase in vehicle speed even if I keep acceleration pedal steady. Speed dicreases when I turn A/C off.

Yesterday I have done the following tests:
1. If I switch A/C on when idling, this produces only a slight increase in rpm (up to 900) for a second, and the rpm goes back to 750-800. Which I think is fine?
2. But if I depress gas pedal to keep, for example, steady 1500 rpm and then switch A/C on, the rpm rises up to 4000! It rises slowly - in about 2-3 seconds. Then it stays there for a few seconds and drops back to 1500. if I turn A/C off rpm drops back to 1500 also.

Any ideas whout could cause this behaviour?