Lutz

car 1997 Canadian S6 - no heat only cold air from all ducts...was working fine until there was a whistle noise interior got rather warm even at 68F after restart only cold air from all ducts.
Hoses from engine to fan box are warm/hot
vacuum lines near heater box seem fine..
where is the motor located that operates the flap for hot/cold air circulation?
Any help would be greatly appreciated..it is rather cold in Canada....thanks

yodasfro

under the cowl and wiper motor cover.<ul><li><a href="http://www.audi.auto.ru/climate/temp_flap_repair/temp_flap.htm">http://www.audi.auto.ru/climate/temp_flap_repair/temp_flap.htm</a</li></ul>

kinderutz

heater core inlet/outlet hoses get hot, valve is operating, i even moved the flaps manually and still no heat...i ran out of ideas

quattro5.v.2

first thing, check the temp sender using the CC head diagostics to ensure it's getting the right info about the water temp, and pull the CC codes which should tell you very specifically if the temp flap motor is hozed. this will take you 2 minutes max and you don't have to disassemble anything.

assuming it is the temp flap motor, there's good writeups for how to take it out. then find the doc about how to disassemble and clean the servo motors. doing the temp one is easy-peazy - all done from under the hood.

you can buy a new one but they're a little pricey and I believe after doin the re-hab it's not necessary at all. one tip about the documentation - it doesn't really emphasize or illustrate how invisible and easy to lose the 2 little copper tabs that slide in the brush slots are when it comes apart. mine is running fine missing one on one side (its someplace on my electronics workshop floor but I'm damned if I can find it...) but I'm sure its better with it in there. after cleaning brush crap out of there, the motor works 100% good as new. if you STFA a fair bit you'll find some people don't like the brush re-seating/re-shaping process - I don't think that's necessary either, mainly just cleaning the junk out of the commutator gaps with a knife blade or micro-screwdriver does the job and it's good as new. I gave a quick blast of no-residue contact cleaner as well which is highly recommended.

in an emergency or time/part limited situation - like facing a long drive in negative temps - you might be able to disconnect the linkage and temporarily wire the temp flap to full hot and live with manual fan control. you have to disconnect the motor for two reasons though - 1. you can't force the flap with the motor connected without breaking something, and 2. if the position pot and/or motor and/or temp sender are screwed up but still marginally working it will keep trying to move the flap closed on you. but you have to be careful - you can end up breaking the plastic linkage connectors if you try to force something. actually I'd remove the servo motor completely, as it's pretty tough to properly disconnect the linkage without taking everything apart anyway, you might as well pull it and then can set it aside to re-hab later...

Lutz

it was the temp flap control motor. After checking codes - they really did not help much -I took the motor out tested it - it moved only in one direction. I replaced it with a working one out of my S4 and all works A1 again.

Thanks for your help

MonroeS4

My 2000 S4 has a lack of heat too. Pulling the codes the Temp. flap pot. always reads "0". I will have to go out tomorrow and try to locate the flap motor. I'm getting 60 degree air when the motor is at 176 and outside temp is 30ish here in NY. This info will be very helpful. Thanks, George

yodasfro

<ul><li><a href="https://forums.audiworld.com/a4/msgs/2827215.phtml">https://forums.audiworld.com/a4/msgs/2827215.phtml</a</li></ul>

MonroeS4

Thanks, this is exactly the info I need. The odd thing is that the reading is "0". I would have expected a 3-digit number like all the other flap readings I took. The other flap readings changed as they were cycled. I looked closely under the dash today but it was 20 degree and I have to do this outside so it as brief. Couldn't see anything but did find some foam material lodged in the footwell heater duct on the passenger side. So there may be some obstruction inside.
I'm the second owner I think, but there were 3 wholesale trades between me and #1. Heat was bad last Feb when I bought it (126K) but the thermostat was bad. Did the timeing belts, W/pump, thermostat and now eng temp is perfect but still no cabin heat. Cabin filter is new, heater core is bled, water pump is new. Then I pulled the codes using the heater controls and got the "0".
I'll let you know what I find. I may try the second shortcut method soon.