I followed Tony's (V1UHOH) lead and removed, disassembled and cleaned the blower fan and AC "radiator" unit in the S4 this weekend.  Folks, this is a simple procedure, and makes a definite difference in how well your AC works.  Being black on black, my car needs all the boost it can get.  I don't know if you can get the fan out without taking the hood off; mine was off anyway, so I decided to go ahead and give it a look.  My car is an '88 S4, YMMV.

1. Remove the plastic cover which covers the blower motor, wiper assembly and auxiliary washer reservoir.

2. Remove the bolt holding the front valance to the front left fender.  It's square in the corner below the rear passenger side corner of the hood.  This will allow the valance to flex and you can squeeze the blower by it.

3. Disconnect the blower fan, it's a two-wire connector.

4. Remove the rubber gasket/connector that fits between the fan and the AC unit.

5. Remove the two topside screws holding the fan in place.

6. Get up under the passenger footwell, directly above the fuse pane, and locate the recirculation flap, and remove the 2" screw from the trailing edge of the grill.

7. You should be able to lift the blower motor up and out, by CAREFULLY flexing the valance and twisting the fan slightly. 

8. Get a flashlight or shop light, a shop vac with a narrow extension, fix a buck of hot, soapy water with a scrub brush, and grab a beer while you're at it.

9. Remove the by-now-infamous resistor pack from the leading edge of the AC housing.  It has a black plastic connector which pulls straight off, revealing two screws.  Once you remove the screws, the resistor pack can be pulled out from the inside of the housing.  Remove the single screw holding the AC thermostat probe and GENTLY pull it straight forward about 5 inches until it's clear of the housing.  It's a straight piece of wire, but is delicate.  The wire lead on mine was yellow.

10. Take your light, and prepare yourself for the worst.  Peer into the AC housing.  You'll probably find a thick layer of black, sooty lint and various other organic matter.  I had bugs, a feather, hair, and everything else but the neighbor's dachshund in there.

11. Using a soft brush and the shop vac (I alternately used an old toothbrush and a slightly stiffer vegetable brush - no salad dear, I'm stuffed) brush top to bottom on the radiator fins until you get as much of that crud out as you can.  It's a slow process.  When I was satisfied I'd gotten as much of it off the fins as I could, I gave it a good drenching with Windex and then hit the fins again with the vegetable brush, then wiped the entire inside of the housing down with a rag. 

12. Carefully clean the probe and reinsert it back through the hole in the housing and between the fins, looking into the AC housing as you do so.  DO NOT force it, and try to get it back into its original position.  Re-attach with the single screw.

13. Carefully clean the resistor pack.  I used the toothbrush again, and blew it clean with the compressor.  Use contact cleaner if you have it.  I also used an emery board and scuffed the contact points of the metallic flap.  Some advise tweaking the distance between the contact points, as this is supposed to be responsible for the mysterious blower syndrome, but I left mine alone.  Re-install the pack and reconnect.

14. At this point, I also removed the center vent in the console opened the flap, and hit it with a strong blast of air, hopefully with the result of forcing any leftover crud back out the other way.

15. Now for the blower motor...  Remove the 1-inch clip holding the cover over the terminals to the motor itself, and disconnect the two wires from their terminals on the motor.  Remove the 5 pressure clips around the perimeter of the housing.  There's also a small one - at least on my car - on the exit side of the housing.  Remove the single screw from the top of the housing near the center, which anchors the motor to the housing.  The bottom of the housing will now drop away.  Drop it into the hot soapy water.

16. You should now be able to carefully remove the motor and fan from the top of the housing.  Drop the top of the housing into the bucket, too.  By now you should be ready for another beer.

17. If you're lucky enough to have a compressor, fire it up and blow as much of the dust and dirt out of the motor as you can, and follow that with contact cleaner.  Now's a good time to check the condition of the brushes, as well, and make sure the contacts on the rotor are clean.  Mine were, but I suppose you could use a dry toothbrush to scrub them a little if there's anything stubborn left on them.  I put a drop of oil on the exposed area where the rotor meets the bushing.  Clean the fan blades as best you can.  I used Windex and the soft brush, holding the "blades" vertically so as not to get anything in the motor.  Set aside and allow to dry. 

18. Scrub the two fan housing halves, wipe dry and reassemble by pushing the motor back into the top of the housing, reconnecting the wires (they only go on one way), replacing the cover over the terminals, aligning the screw hole in the housing with the respective hole in the motor and then securing it with the screw.  Reattach the bottom half of the housing and replace all clips.

19. At this point I fired up the car, and checked the operation of the recirculation flap located above the fuse panel.  You can look straight down into it while the fan is still out.  Luckily, mine worked fine.  It should open (go into a vertical position) when you move the climate control lever from the rectangular symbol to anything but "OFF", and turn on the AC.  If you're satisfied it works correctly, turn off the car and use either the vacuum or compressor to suck/blow any remaining debris out of that area.

20. Flexing the valance carefully upward, replace and remount the fan unit.  Try not to drop the screws, as they're a bear to retrieve.  Don't ask me how I know.  Don't forget the one that goes in from underneath, through the trailing edge of the flap grill.  Replace the bolt holding the valance to the front right fender.

21. Scrub the rubber connecting gasket, dry it, and hit it with some Armor All or similar product.  As a precaution, I cut a rectangle of netting (similar to the plastic netting used on screen doors) and put it around the AC housing side opening, and secured it with a big rubber band.  It doesn't affect airflow, and should stop any large junk that would otherwise get blown in through the fan.  An ounce of prevention...  Remount the connecting gasket, with patience.  Fire the car up, open the windows, and check the AC with the fan set to 4.  I had a noticeable difference both in the force of the air and the temperature of the AC.

Don Davis
CPOCMA Systems Mgt Div.
5440 Student Drive
APG, MD 21005
DSN: 458.1749/Com: 410.306.1749
Fax: 458-1776
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