i have a 99 A8Q. Having a problem with the blower operation. one year ago blower motor was no good. replaced motor & it was fine for six-7 months.Then the motor was staying on high killing the battery with the key off.Replaced the blower regulator module, again it was fine for 6-7 months. Now the blower does not come on at all. If I put a fluke meter across the two wires for the motor, there is battery voltage with the key on or off. When i plug the motor back in & backprobe it there is barely 1 volt. I'm not %100 sure on how this system is desiegned to operate. Any help or direction to links would be appreciated.

 

The low voltage drop across the motor indicates that it has low resistance. I have a feeling that it constantly being on shorted it out. Try hotwiring the motor to 12v and see if it turns. If it doesnt, replace it.

 

The motor does turn with 12V to it. Im thinking I may have a faulty connection somewhere between the control head & the blower module/blower motor?????????Or a short to positive or ground.
Gonna start diggin on saturday.

 

Unfotunatly i dont have a wiring diagram so i can only speculate at blower operation but i suspect that the motor is controled on the ground side, due to the fact you have 12v at all times wheter the key is on or off. Check to see if your getting a ground between the motor and battery by placing the positive lead on the gound side of the motor and the negative lead on a good body ground. If you get 12v you dont have a ground. Wheather that is from a bad control module or a bad control head, im not sure. You may want to check the ac system for faults using a scan tool and seeing if that gives you any clues as to where the problem lies.

 

I Cant Communicate With The Control Head Either.

 

If powers and grounds to the module are ok and the databus wires are ok at the module, your gonna need a new module. Without the wiring diagram i cant help you find what wires to probe.

 

Weel I figured it out. After 2 solid days of rain in Ct. I went to work disconnected everything on the circuit with the blower motor.No shorts to power or ground.One by one I plugged every body back in until i got ground when i wasnt supposed to. You were right the module had shorted out again!!!!This time I found out why???When it rains or I wash the car the chamber where the bower motor/module are was filling with water. Found the drains clogged solid. Had to pull the module out, then drilled a small hole in the bottom it was filled with water. After seeing that I had to pull apart the box on the pass. side with the ECU's in it and dry them out as well. Seema to be working perfect now. WATER IS THE ENEMY!!!!!!!

 

You got that right. Just imagine your electircal problem times 100 and you have a flood car. Not fun at all.