No A/C, where to start?

brotherhay · Post by **brotherhay** » Sat May 01, 2010 10:26 pm

Ive been going over this 1980 528i and taking care of as much miscellaneous issues as I can. The list is getting short, but with the warmer weather coming, I would like to give the A/C a shot.

In a previous thread I was chasing down why my aux fan would not turn on. I have tested the fan and it works, but when turning the climate controls to cold and turning on the fan, the aux fan never turns on. From what I understand this is supposed to happen. Ive read of a diode that can fail, but seems to fail open and not closed. Id like to find where that is, thats an easy test and fix if it is a problem. I dont think I need to be concerned that the controls themselves could have issues. If I turn it to cold and the inner blower motors turn, then I feel that selection is being recognized properly. If theres more to it with the controls, Id love to hear it.

I figure Ill chase this problem down first to get into the A/C. There for sure is no cold air blowing currently but I do know that aux fan is necessary to this process. I think Im actually lucky enough to have oil and freon left in this car.

Mike W. · Post by **Mike W.** » Sun May 02, 2010 12:16 pm

I'm unclear, does the A/C blower in the console work or not? If it does, then you have to figure out if you have power to the A/C compressor clutch, since it doesn't sound like it's turning on. There is a little microswitch actuated by the temperature dial that likes to fail but if it's bad you would have no A/C blower. There's also a thermostat in there too which cycles the compressor, again, actuated by the temp dial.

brotherhay · Post by **brotherhay** » Sun May 02, 2010 10:39 pm

The A/C blower inside the car spins, thats correct. The Auxilliary fan does not. Its easy enough for me to test the compressor and see if thats getting power. If no power, then its off to the parts store once again.

Mike W. · Post by **Mike W.** » Mon May 03, 2010 2:13 pm

Yeah, the thermostat might be bad then, you probably will not have power to the compressor. The stat is up in the controls behind the 3 dials. A silver box with a lever on it. They do pretty well unless the cap tube gets tweaked which can easily happen if you in there. The end should go into the evaporator box.

pappentl · Post by **pappentl** » Mon May 03, 2010 5:59 pm

How did the test of power to the compressor come out? I've had issues in the past with my compressor kicking on; it was a ground issue. The test was to start the car, turn on the A/C then with a grounded jumper cable touch the compressor, in my case it sprang to life, so I fixed the ground to the compressor and had nice, cool A/C. YMMV.

...tom