A/C Systems - 4000 series

[Mihnea Cotet]

Hi Colin!

>All the wiring diagrams I have seen show multiple electrical controls >that 
>I
>cannot find. I wonder if I can ask those who have had the panels off >their
>84-86 4000s or Urqs with A/C to respond to these questions:

That's what I'm trying to do!

>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.

>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.

>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.

This info is from a type 85 1985 German Coupe quattro (136 hp) with A/C 
which should apply to your car.
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.

Hope this will help, I can't tell you more about the voltage issue. I've 
just removed the A/C from my car as it weighs too much and doesn't allow me 
to put an oil cooler in, so I won't be able to tell you much more about 
this...BTW if someone is looking desperately for a good A/C compressor that 
doesn't leak, feel free to email me.

Regards from Belgium,



Mihnea

'85 Coupe quattro (still stock but waiting for a 2.5l low-pressure turbo 
upgrade, konis and a complete stainless steel ehxaust system)

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