S4 HVAC - Miniature person stuck in my dash!
10-19-2007, 10:35 PM
#1
Rennlist Member
Thread Starter
Join Date: May 2004
Location: Seattle
Posts: 1,020
Likes: 0
Received 0 Likes
on
0 Posts
S4 HVAC - Miniature person stuck in my dash!
This guy really wants out of my heater, but it seems the door he is trying to exit won't open all the way. That doesn't keep him from trying though. He sure makes a lot of noise for such a little guy!
So anyway, yeah, on my '91 S4. 90k miles and the car sat for a couple years before I resurrected her. No major issues from the HVAC during the first 500 miles back on the road other than non-cold AC and a slightly (very faint) hissing vacuum sound when you have the control lever in the triangle "up" or triangle "up and down" position.
Until yesterday, that is. When first starting the car, you hear a tap-tap-tap from the center vent area. It seems to be vacuum related as you can make the sound happen when on the gas and making more vacuum. Also, you can make it happen with turning the key "on" after running the car without starting the engine until the saved-up vacuum is gone.
It seems like you can affect the way it happens by the temp adjuster. Maybe it is the door that allows more/less heat in from the heater core? It also sounds very much like the sound when you manually close the center vent. It will make the sound with the center vent open or closed.
I know the next step is to start checking for vacuum leaks and bad modulators and such. Either I or the shop will but maybe someone has experienced the same thing?
So anyway, yeah, on my '91 S4. 90k miles and the car sat for a couple years before I resurrected her. No major issues from the HVAC during the first 500 miles back on the road other than non-cold AC and a slightly (very faint) hissing vacuum sound when you have the control lever in the triangle "up" or triangle "up and down" position.
Until yesterday, that is. When first starting the car, you hear a tap-tap-tap from the center vent area. It seems to be vacuum related as you can make the sound happen when on the gas and making more vacuum. Also, you can make it happen with turning the key "on" after running the car without starting the engine until the saved-up vacuum is gone.
It seems like you can affect the way it happens by the temp adjuster. Maybe it is the door that allows more/less heat in from the heater core? It also sounds very much like the sound when you manually close the center vent. It will make the sound with the center vent open or closed.
I know the next step is to start checking for vacuum leaks and bad modulators and such. Either I or the shop will but maybe someone has experienced the same thing?
10-19-2007, 11:01 PM
#2
Rennlist Member
Thread Starter
Join Date: May 2004
Location: Seattle
Posts: 1,020
Likes: 0
Received 0 Likes
on
0 Posts
Duh... this sure seems like the problem...
<A black plastic "comb" flap inside the center vent assists the mixing of air for temperature control. An inoperative flap is closed which does not allow maximum air flow for A/C cooling. A partially working flap can also flutter making a chattering noise.>
<A black plastic "comb" flap inside the center vent assists the mixing of air for temperature control. An inoperative flap is closed which does not allow maximum air flow for A/C cooling. A partially working flap can also flutter making a chattering noise.>
10-20-2007, 02:04 PM
#3
Rennlist Member
Rennlist Site Sponsor
Usually a leaking diaphragm in the comb flap. Temporary fix is to plug the orange vacuum line that feeds the flap actuator, permanent fix is to replace the diaphragm or actuator.
10-20-2007, 08:49 PM
#5
Addict
Rennlist Member
Rennlist Member
See:Plenty of photos and instructions to get you through this.
10-20-2007, 10:52 PM
#6
Deer Slayer
Lifetime Rennlist
Member
Lifetime Rennlist
Member
I thought this thread was going to be about how your kid stuck a little action figure in your vent. I was going to follow up with a mildly amusing anecdote about the time I had to remove a toilet that kept getting plugged and found "HE-MAN: STRONGEST MAN IN THE UNIVERSE" wedged in the drain pipe, but I won't go into any more detail.
