Mechanics

QUATTRO COOLING FANS

1997 Audi A6

RECENTLY BOTH COOLING FANS ON THE CAR HAVE STOPPED RUNNING. THE CAR HAS BEEN OVERHEATING IN TRAFFIC. ALSO, WHEN THE AC IS TURNED ON THE COOLING FANS DO NOT RUN AS THEY HAVE IN THE PAST. THE QUICK AND EASY FIX, AND ONE I HAVE DONE IN THE PAST, WAS REPLACE THE COOLING FAN THERMAL SWITCH IN THE RADIATOR. THAT DID NO GOOD. USING THE BENTLEY MANUAL FOR THE CAR I DISCOVERED THAT IT IS MISSING MANY OF THE CIRCUITS RELATED TO THE AC SYSTEM, AND THE LAYOUTS OF THE RELAY AND FUSE PANELS HAVE ERRORS. I HAVE SINCE FOUND MORE ACCURATE DIAGRAMS AT ALLDATA. I HAVE LOCATED AND CHECKED THE FUSE, THE 2 FAN CONTROL RELAYS, B+ TO THE RELAYS, POWER TO BOTH CIRCUITS INTO THE FAN CONTROL THERMAL SWITCH, AND THE GROUNDS. I HAVE SYSTEMATICALLY JUMPERED AROUND EACH COMPONENT EXCEPT AS NOTED BELOW AND EVERYTHING SEEMS OK. THERE IS A POWER RESISTOR TO REDUCE THE FAN SPEED THAT I CANNOT FIND, AND I CANNOT CHECK THE FANS, AS THE POSITIVE LEAD TO BOTH OF THEM DISAPPEAR INTO A GROMMET IN A 'CHASSIS' MEMBER IN THE FRONT LEFT CORNER OF THE ENGINE COMPARTMENT. MY NEXT MOVE WILL BE TO RELUCTANTLY PEEL SOME INSULATION OFF OF THE FAN MOTOR LEADS AND CHECK THEM OUT, THOUGH I CAN'T BELIEVE BOTH OF THEM FAILED AT THE SAME TIME. THE ONLY PLACE I HAVE NOT BEEN ABLE TO TEST OR JUMPER AROUND IS THE POWER LEAD TO EACH FAN FROM THEIR CORRESPONDING RELAYS AS I DON'T KNOW FOR SURE WHERE THE LEADS GO AND THE COLOR OF THE LEADS DOES NOT MATCH THE WIRING DIAGRAM. ANY HELP WOULD BE VERY GREATLY APPRECIATED!
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Diggypiff
July 20, 2007.




Are the fan relays getting " trigger" when the a/c is turned on?

Tiny
Jack42
Jul 20, 2007.
HI JACK. YES, THE TWO FAN RELAYS ARE BOTH 'TRIGGERING' WHEN I TURN THE AC ON, JUDGING BY FEELING THE RELAYS CLICK ON AND OFF AT THE SAME TIME AS THE AC CLUTCH. IF YOU NEED ME TO CHECK THIS WITH A METER I WILL HAVE TO WAIT UNTIL SUNDAY AS THE CAR IS NOW OUT OF MY POSSESSION UNTIL THEN.

DOUG

Tiny
Diggypiff
Jul 20, 2007.
If the relays are getting trigger, then trying to jump power straight to the fans might be a good idea just to be sure they are ok
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Tiny
Jack42
Jul 21, 2007.
HI. I WAS ABLE TO FIND THE SPEDD REDUCTION RESISTOR, N39, YESTERDAY. IT IS MOUNTED UP UNDER A FRAME OUTRIGGER IN THE FRONT LEFT CORNER AND ACCESSIBLE IF THE SPLASH PANEL IS REMOVED. POWER IS GETTING TO THE CONNECTORS THERE, SO I DISCONNECTED THE LEADS TO THE FANS AND CHECKED CONTINUITY TO BOTH OF THEM AND BOTH FANS ARE OPEN. ITS POSSIBLE THAT ONE OF THEM BURNED OUT SOME TIME AGO AND DID NOT GREATLY AFFECT THE COLLING PERFORMANCE, BUT NOW THE SECOND ONE HAS BURNED OUT AND NOW I HAVE COOLING PROBLEMS. I WILL REPLACE THEM AND CONFIRM WITH YOU THAT THE PROBLEM IS SOLVED.

DOUG

Tiny
Diggypiff
Jul 23, 2007.
Look forward to it

Tiny
Jack42
Jul 23, 2007.

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