[s-cars] A/C problems

[George Verbryck]

My A/C is acting up I noticed that the fan does not come on thus I am pretty sure this is at least part of the problem. I looked in the archives but could not find anything . So when you push the A/C auto button I assume the control unit tells the fan to come on? Is there a relay? I looked at the A/C diagnostics list but could find no mention of the fan so... Where do I start for the trouble shooting? the fan seems to work if the car has no A/C on and it gets hot enough to kick it on. Patient is a 93 S4. TIA
George