PeachParts Mercedes-Benz Forum - View Single Post - W124 climate

Diseasel300 · #2 04-14-2017, 11:53 AM

The Klima relay controls the A/C clutch. It won't be your issue here, especially since the refrigerant has leaked out.

I'd suspect the issue lies in the pushbutton unit itself or the "porcupine" blower motor controller, although you said you just replaced that.

My SDL (which has a similar HVAC system) had goofy fan controls in "Auto" as well, it only ever seemed to blow full or blow low and there was no real rhyme or reason to what it was doing. High fan and Low fan would produce the proper results, but "Auto" was all over the place.

I got brave and rebuilt my pushbutton unit in a desperate attempt at getting some A/C. One of the things I did was replace all of the electrolytic capacitors on the circuit board. In addition to getting my compressor working, it also seems to have restored proper operation of the "Auto" fan function. Instead of just abruptly changing between high and low randomly, it seems to gradually change speed and hold at various levels depending on where the temperature is set and what the temperature of the car is. Very clever...