hi! This may be the old question from other guys.

I have 87 MB 190E 8V, the A/C doesn't work when I bought the car last winter.

Now, I want to fix it. I put the used nice compressor on (from 92 MB 190E only 65000km) and did the leaking test. I should no leaking on the A/C system.

The questions is when i try to refill the feron, the compressor not kick in. Now, I am not sure is it the climate control switch problem, A/C relay (behind the battery one), or Aux fan relay (in R2 position fuse box). I touch the aux fan relay, it is very hot, but I never see the aux fan turning.

It really seem no power to compressor.

Any suggestions, please help.

The "pushbutton" control unit sends a GROUND signal to the low pressure switch on the drier & that signal goes to pin 10 of the KLIMA (compressor clutch relay). Do you have that signal?

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I put the other used climate control switch and other aux fan relay on, but the A/C compressor still not working.

I will put the A/C compressor on tomorrow and see what happened.

I will update later.

Today, finally make the compressor kick in after I replaced the A/C Relay.

Now, convert to 134a