Diagram of HVAC Venting?

[Ti Kan]

Ti Kan wrote:
> With the hood up and the plenum cover off (that black plastic rain drip
> thing that also covers the wiper motors), you should be able to see the
> vacuum solenoid operate when you move the temperature lever to full
> cold and turn on the A/C.

David.Ullrich at ferguson.com writes:
> OK, the "evaporator" (I can never keep straight the evaporator and =
> condensor)is getting plenty cold. That little vacuum solenoid DOES move =
> when the AC switch is flipped on. But I don't hear any change in air =
> flow nor does it seem to change the air flow pattern/amount. Any =
> suggestions on what to look at next?

If you look into that air box from the passenger side opening you should
actually see the air flap move.  If that's moving ok then it should be safe
to assume that all is well there.  I don't think you'd be able to hear/feel
any change in air flow pattern or amount within the cabin by that alone.
On these cars, the air flow pattern is manually regulated by the two
levers at the control panel, and the flow amount is governed by the
blower fan speed.

Since A/C cooling is controlled by cycling the compressor on and off on
these cars (rather than mixing ambient v. cooled air like on other
more modern Audis), you might want to pay attention to see if your
A/C compressor clutch is cycling, and if so, what is the duty cycle
(how much time on and how much time off).  If the compressor is not
running much then maybe the temperature control needs adjustment.
Note, though, that there is also a capillary tube that runs from the
temperature control to the evaporator, that overrides and turns off the
compressor to prevent the evaporator from icing up.

-Ti
01 S4 2.7 biturbo quattro
84 5000S 2.1 turbo
80 4000 2.0
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