W126 280SE Euro

When I switch on my car air conditioner, the engine idling become too slow at 350-450rpm, when turn off the a/cond the idling go back to normal 800-900rpm. Any hints as to what (Part & location) could be the cause of the
problem would be greatly appreciated.
TIA, Marks
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Replace the compressor or recharge the system? The engine will be under load as the AC in on, to much load means something is working overtime. At idle in gear my 400E goes from 600 rpms to 450, It might be pretty close or your engine is getting old. Was it different before that?
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o
wrote:

Thanks for the reply, sorry to mention that the idling speed was normal week ago, it was 850rpms (speed drop to 650 for one second then back to 850rpm) even after switching on the a/cond. It seem something is controlling and to increase the idling speed while air-cond is switching on ?
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There is two things to control idle speed... idle speed control'er (these do go bad) and the air valve in which it controls the idle speed.
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