I've done some research in the archives on the Klima Relay. However I want to make sure that the following is correct...

To activate the compressor, output 87 is given +12V
(it's a bit unclear wheter the compressor is engaged with +12v or a ground signal).

Is the output 87z put to +12v to signal the ECU to increase the idle? Alternatives are +5V TTL-level or a ground signal..

The Klima relay being analyzed has part # 002 545 13 05.

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99 W210 E220 cdi sedan automatic (248.000 km) 210.006

Yes the 87 terminal needs 12V & goes to the A/C compressor. The terminal 15 right beside the 87 is power (12V) with the key on.

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Thanks! I'll be busy troubleshooting stuff this weekend now

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99 W210 E220 cdi sedan automatic (248.000 km) 210.006