searchin99

A new problem has cropped up in the past few days - the air conditioner fan seems to have gone on intermittent status. Some times it'll come on and sometimes it won't.

Symptoms:
(1) So far it seems to work more often, probability-wise, the first thing in the morning when the car is cold.

(2) It seems the compressor is working when the fan isn't, but I'm not positive on this yet.

(3) Sometimes it'll kick on for no apparent reason after having not been working for a while.

(4) When the AC fan won't work none of the other fan settings like econ air will work either.

(5) the 30A AC circuit fuse is okay.

Does this sound like it might be the AC relay (Bently Audi 100, 200, p. 401, relay position #4) in the Auxiliary Relay Panel under the dash?

Editorial Comment: these items are expensive!

Randolph

I'd look at the blower control unit, assuming the 91's have one. When these go bad they cause the blower to act squirrely. In my case it was high speed fan all the time when the car was running no matter what setting I had the cc head at.

Randolph
87 5KCSTQ
93 928GTS

Kneale Brownson

It's your blower motor dying. Hit a bump or turn a fast corner and the squirrel cage moves just enough the thing can start spinning again. That motor runs whenever the car does unless the HVAC system is switched completely off, so they have a limited life.

It's a real PITA to fix too. The blower motor is in the leading edge of the heater core box in the middle of the HVAC well under the rain diverter at the base of your windshield.

The link goes to some information provided by Chris Miller on his 200q20v page on the procedure. It'll be about the same for your 100 as for the 200. Some folks do a complete heater core replacement "while in there". I've replaced a couple blower motors without doing the heater core itself and continued to get years of service out of the core.<ul><li><a href="http://members.aol.com/c1j1miller/climate.html#Heater%20blower">heater/blower stuff</a></li></ul>

mofologic

BTDT on my 91 100 - intermittent and then nothing until I pushed the brushes further down with a wooden dowel and hit them with WD-40. have gotten another 2-1/2 months so far without having to either replace brushes or the entire motor assy (PITA from what I have read).

anyname

I just pulled the heater fan out of a 91 200 and put it in my 86 5ktq. After getting it into the 5k the fan still wouldn't work. After some trouble shooting I found that the control unit was toast. I put a ground in the proper place ( control unit controls the ground to control speed of fan) and it works fine...It just works all the time There is a shortcut to replacing the fan.

http://www.sjmautotechnik.com/trouble_shooting/ac.html

I used this and had the fan out in about 35 min. had the total job done in about an hour. Took longer putting it in because I had a hard time with the interior. The only suggestion I have is to remove the complete wiper assembly and move it out of the way.

searchin99

Thanks everybody for all the good responses and for the helpful links and the "shortcut"! This is a great board!

It's good that others have had prior experience and can pass the lessons learned along. I absolutely hate working up under the dash - I'd almost rather do anything else except that. Ugh!

Here is some more input from the past day.

(6) About 20 to 30 minutes after running the AC I had some "funny noises" emanating from what appeared to be under the hood but maybe in front of the firewall. I pulled over to the side of the road, popped the hood, and tried to see where it was coming from. It sounded like it was coming from near the firewall but under the dash.

The noise sounded kinda like something rubbing/banging against something else - maybe a squirrel cage fan against a flapper something?

(7) The other interesting thing was the AC fan came on apparently at the same time the electric window was rolled down. This may have happened before but it's hard to make the connection. Weird!

(8) As for hitting a bump - our roads, especially with all the road construction going on, have lots of bumps. Ditto with Seattle city streets! Perhaps this may be why the fan kicked on once in a while?

(9) Fan tends to stay on once it's running,... I think.

I don't know if any of the above would alter input/feedback comments.

I really don't relish tearing into work under the dash.

searchin99

Here is some new input after a recent drive:
(a) The car was last stopped with the AC running and when it was started the AC came on and ran, but....
(b) The air flow varied - sometimes blowing hard and other times not quite so, not abruptly but sort of variable.
(c) Sometimes I could hear a slight vibrating sound, like a plastic washboard with something going against the grain.
(d) There was one time that I could hear a muffled-sounding "banging" of something that was probably plastic, as though there was something loose way inside the dash area.

Don't know how the previous update about a possible connection between the power window and the fan fits in, but it seems like the fan might be okay but perhaps a flapper or something similar could be at fault.

Or maybe that is in addition to the fan being a problem - after all, it didn't run at all.

But then maybe there are other controls that would prevent the fan from running?

Called my Audi dealer and the gal said they'd have to do diagnostics first, at $110/hr, before they could quote anything.

Eric NY

Blower moter... Brushes wear out! BTDT every 44 i've owned!...

Eric