Also, I wired the positive side of the fan to the positive side of the battery, kept the ground connected to the fan, and turned the car on. The result was a flawless operation of the air conditioning. Does the operation of the aux cooling fan impact the operation of the a/c compressor clutch? It seems as though it does.

 

Bump?

Please! it's hot down here.

 

Do you have a wiring diagram? Mines for a '96 a6 w2 electrical fans so is differeent.

And yes, you need that fan to run for the A/C to work. Its just like the condensor unit outside your house - it draws the heat outta the refrigerant. If you cant do that, the compressor shuts down.

 

There's more to the diagram, but I figured this part would be the most relevant:

 

Well.. I hate those 'diagrams'. They tell you 'where' and 'what' but not 'how'.

Well, start at that 40A fuse and work your way down. Thats the 'main power' side. On the 40A side, check the fuse. If good, check the input to the J26 and J101 relays (pins 30). Bad? Wiring problem. Good? Start engine, turn on A/C and check the outputs (pins 87). J101 should have power out, J26 will wait till engine is warm. Bad? See 5A side below. Good? Check input to fan. Bad? Wiring problem. Good? No clue since you already ran power with the current ground.

The 5A fuse is the 'control side'. You dont show it, but I would assume that if you do not have power at the 5A fuse, your climate control or fan control could be dead, since they are what 'call' for the fan. If you have the power there, check the coil input sides of the Fan Control relay (J26) and Second Speed Fan relay (J101) (pins 85). Then the output side (pins 86). Ground it if you have too. Bad? bad relay. Good? Check the input to the A/C Pressure Switch. Bad? Bad wiring, prolly at the connector (14-wire). Good? Check the Pressure Switch (jumper the pins on the connector. Work now? Pressure switch is bad. Good? Dont know without more diagram .

Sorry cant be of more help... My diagram also shows a Coolant Fan Resistor that i dont see on yours... with the Coolant Fan Control and A/C Control controling everything

 

I see what you're saying, but do you have any idea where these components would be located in the car?

These wiring diagrams make my head spin.

 

The locations should be in your service manual. I have the locations for most on my my car, but not yours.

maybe someone with the 01 A4 manual will chime in.

 

I have an idea of where to look for these relays, but the manual was a little vague. I'll start the search today. How will I know when the engine is warm enough to trigger the second speed relay?

 

Bump?

 

Just found out that I had checked the wrong 40 amp fuse the first time. I just checked the one for the cooling fan and saw that it was burned out. Any idea why this happened? Do you know how likely it is to reoccur?