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Jake, Technician
Category: Audi
Satisfied Customers: 2429
Experience:  Over 30 years experience, 17 years with Audi, Factory trained
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My 98 Audi A6 AC/heater blower motor is not turning on. I sent

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My 98 Audi A6 AC/heater blower motor is not turning on. I sent the claimate control off to be rebuilt, but it did not fix the problem. I put 12 volts to the plug on the blower with AC on and it works great with ice cold air at the vents. Someone told me it could be the solar panel sunroof "seperation relay" is bad and it would prevent the power to be directed to the motor. I dont want to blow another 100 bucks for a part that I dont need. How can I test the relay to see if it is working? What pins need 12 volts and ground?


Thank you for choosing Just Answer for your query. Yes I can help you.

This answer would be for a 1998 A6 sedan. The 1998 A6 wagon was a completely different vehicle.

First off I do not think this year model has a solar panel in the roof. Is your sunroof clear/tinted, or is it a solar panel?

The blower motor gets it's variable ground signal from the climate control head (you rebuilt) The power comes to the blower from the #25 fuse. Have you checked the fuse? If the fuse is good check for power there with the vehicle running and let me know and I will further assist you.

I hope I have answered your questions and addressed your concerns. Should you have further questions on this matter, please do not hesitate to ask. I want you to be 100% satisfied with my answer.

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Thank You!
Jake “The Audi Doctor”
Customer: replied 8 years ago.

It does have the solar panel roof. I can see the panels on the outside, and if the solar panel is installed the sun roof will not have sliding sun shade screen that you can open and close and mine does not have the shade screen. I did check the fuse 25 and it was good, but I did not check the voltage yet, I will do that today. I do have the relay in question in front of me "4B0 959 589" . I wanted to test it to see if it works but I'm not sure of the pin out's?





OK, you check the voltage and I'll check further into wiring for the solar relay.

Thank You!
Customer: replied 8 years ago.

I checked the voltage and there is 13.6 V. Then I checked for voltage at the blower and it was 0V . The climate controller was suppling a gound to the motor at this point.


So , I need to know what is between the fuse and the blower that could be bad.





OK, The separation relay is between fuse #25 (key on B+) and the blower.

The exact working of the relay is not explained, but terminal #4 (bk/grn) goes to the bower motor, fuse #25 (key on B+) comes into the relay at terminal #5(bk/bl). If you jump between #4 and #5 the blower should function. The solar panel B+ comes in at terminal #6(rd/bl). The relay switches between the #5 (fuse #25) and #6 (solar panel B+) dependent on if the vehicle is running or not. Terminal #2(rd/bl) is B+ all the time from fuse #10 and #1(brn) is ground all the time so I assume that only leaves terminal #8(vio/gray)to be the switching signal from the climate control head.

To test it check;

#2 - B+ all the time from fuse #10.

#1 - ground all the time

#5 - B+ key on from fuse #25

#4 - jump #4 to #5, key on, blower should function

#6 - jump #4 to #6 key off the blower should function if the solar cell is in the sun and roof is closed.

#8 - check for voltage key on and key off = should switch between a voltage signal and not (or vise versa). If all these tests are as described the relay has likely failed.

That should do it. Let me know how it turns out.

Thank You!
Jake and 2 other Audi Specialists are ready to help you
Customer: replied 8 years ago.

You the Man!


Your notes allowed me to test the A/C system without the relay in place and I was also able to apply power to the relay and check for continutiy across 4 and 5 . The relay does seem to be bad. Now I'm tasked with finding one at a good price!


Thanks Jake