A/C Systems - 4000 Series

[colin cohen]

Message: 12
From: "Mihnea Cotet" <mihnea_cotet at hotmail.com>
To: quattro at audifans.com
Subject: A/C Systems - 4000 series
Date: Fri, 29 Jun 2001 22:05:33 +0200

Hi Colin!


>1) Where are the A/C relays.  I know that there is supposed to be one in
>position 11 in the main fuse box. The wiring diagrams show compressor
> >clutch
>relays as well?

Yes, number 11 in the fuse box is the right location for the first relay. If
this one is missing, then this is your problem. The compressor clutch relay
is underneath the dashboard on the driver's side, behind the small glove
box.

***********Do you know what station the relay is installed.  I have 2 relays
at positions 14 & 15 which are the second and third from the left on the top
row of the under dashboard driver side panel.  These are indicated as not
installed on the sticker you refer to later.  What do you have installed in
those positions.  BTW, the Euro VAG Workshop manual says that the A/C  is
installed in station 4 which is the 4th from the left in the center row.
However the sticker says that this is a headlamp relay (in German I think it
says Hauptlicht relais).

This is amusing because I always though that there were no headlamp relays
in the mid-80 Audis which accounted in part for their poor performance.
But perhaps the Euro Urqs did have relays. Perhaps others can shed some
light on this side question?

>2) There is an A/C thermostat and microswitch marked on several wiring
>diagrams I have seen.  But there is no reference to their existence
> >anywhere
>else in the Bentley or the Euro workshop manual I have obtained?

IF they exist, they should be at the same place as the compressor clutch
relay.

******** What - on the panel?  There are a couple of fuses in station 17,
second from the right end, top row, but no sign of anything else.  Others
responding say that these are adjacent to the RHS of the evaporator.

>3) Are there any other electrical or cut out devices other than the
> >pressure
>switch?  Where is the pressure switch installed?  Mine is on the dryer >and
>is only getting about 6 volts from the live wire.  This is not enough to
>kick in the clutch.  When I jump 12 volts to the clutch it activates.  >So
>something is possibly reducing the voltage. Any ideas?

Don't think so...normally there shouldn't be any. Try to find where the
voltage drop is. Sorry, but I don't have any other idea.

****** That's OK, I will search it out once I find the pieces on the wiring
diagram.


The underdash relay chart is printed on the rear_of_the_back (!!) of the
small glovebox so when you take it out, you can see what relays are in front
of your eyes (might be in German, though). There is also a fused ABS relay
in there, so when you have ABS problems, this is where you should look at if
the underhood fuse is ok.

************ See above - I figured that one out too.  There is no reference
to these relays in the manual.


Colin