ok,here goes...its a 91 100 and has the electronic climate control system. After adding freon to get every thing up and running, when i use defrost or other settings the compressor kicks on but the condensor fan will not come on. So I disconected the compressor and found a 90 100 parts car with the a/c working and switched out the elec control head and the blue fan speed relay plate next to the radiator. Still the fans not coming on, only when the car is up to temp than shuts off as it cools down. Is there anything that might help that i might be missing, like a relay or a fuse thats hidden somewhere? Can i use the 84-88 5000s 5000cs Bentley to help me on the 91 and how do I remove the glove box? mine slides out to check if my fresh air flap spring is broken, if thats whats making my windows fog, or does the a/c need to be working to help with defogging ?

1 when the defroster is on it kicks your ac as you know. so if the ac isnt quite working right it wont defog fast.

2 if the ac works and it blows heat but the windows are still foggy it might be a crack in the heater core.

not exactly sure what to tell you with it just some round about answers for the heater core. does it smell like antifreeze when it is on?

No antifreeze smell at all but to check the air flap under the glove box I need to get it out of the way. Here is something weird, I found that interior dressings can emit gases that will also fog up windows, now thats a new one on me. By the way I am pretty well seasoned in working on cars but this Audi is very quirky.

The blower should only blow on the "defrost" setting until the car reaches normal operating temperature.

The old Bentley HVAC section is pretty similar, although I don't know if it has identical test procedures or specifications.

If you open the glovebox and put your head in the passenger footwell, you should be able to look up and see whether the recirculation door is open or shut. It should be shut for all heating operations. It should be open for cooling during A/C use.

The glovebox itself is held in place by a couple Alan head bolts that hold the upper glovebox assembly frame to the dash structural elements. Something like 4 or 5 mm. You need a really short Alan wrench (shorten standard L-shaped shorter arm some) to get to them. If I remember correctly, just loosening the bolts will allow you to shift the glovebox assembly slightly toward the end of the dash and it will drop off the screw heads. Some folks report they can repair the recirculation door with the glovebox in place, but I'm short and fat with heavy arms, and needed all the room I could get.

yes but the cooling fan should come on when i select defrost or soon after the compressor kicks on yes or no ? i just dont want to blow the charge or the a/c lines. could the low pressure or high pressure switch be bad? where does the signal come from to start the coolant fan when the a/c is in demand ?

The blower motor (for heat or cooling) should start as soon as you hit the defrost button, regardless of the status of the A/C compressor. You should not need an A/C compressor in order to run the blower motor when on defrost mode. Moisture control in defrost mode might not be as good as it should be if there's no compressor operation, but defrost still should blow air out the dash vent. If you're having a window fogging problem, it's most likely the recirculation door being open when it shouldn't be. Default position for the recirculation door is shut. It remains open if the door has an obstruction like the dead mouse someone once reported or if the spring is broken. The fan gets its initial signal to operate from the climate control head. Power passes through a sensor that's under a little trapezoidal plate on the top of the evaporator box. There are some electrical connectors on top of that plate. If your fan is not coming on appropriately, however, it well could be the blower motor is beginning to fail. If the fan sometimes fails to start until you hit a bump or make a sharp turn, the motor is deteriorating.

looks like a piece of paper got in there some how i did have some luck removing it wow was it stuck on there

after cleaning the fins and fixing the flap spring its blowing air out of the vents like never before now that should help with the fogging problem thank you for all your help