I was using my a/c last night when the engine temp starting rising and I felt warm air coming out of the heating duct. I checked the aux fan today by jumping the switch and the fan did not work. I checked the fuses for the fan, no power at either side of the fuses. I see there are two relays for the fan as well, I tried switching them out since they had the same part #'s, no good. Also the heater valce has no power going to it as well which would give the impression the valve went bad or the diaphram is shot, but I rebuilt it about two years ago. The A/C switch doesn't light up either and the a/c compressor doesn't engage. Am I missing something or are all of these units tied together? Maybe there is a climate control module/ relay that I can't find in a diagram? Please help. 1983 633csi

I figured it out!! It was a blown fuse #17. Someone before me put in a 7.5A fuse instead of the 15A fuse. That fuse supplies voltage to relay K5 which in turn supplies voltage to relays K1 & K6 for the aux fans. Also I believe K5 supplies voltage to a/c and heater valve. I didn't get that far, but replacing fuse #17 made everything work.