A/C Systems - 4000 series

[colin cohen]

I have been struggling to repair my A/C system for the past several weeks.
The problems have been exacerbated by what seems like defective rebuilds of
the Sanden compressors. It has not been helped by my cluelessness about the
system.

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:

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?

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?

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?

BTW - the car is a Sport Quattro but I believe the A/C is a Euro 4000/Urq
installation.  Its activated by a snow flake marked button in a panel to the
right of the steering column where there is also a recirc. button.  It is
wired through the blower switch so that without the blower being on it
cannot activate.  When I press the snow flake with the blower on, the
radiator fan kicks in (as it should), there is a click from a relay in the
sub panel under the dash (when 12 volts are jumped to the clutch) but
otherwise nothing else happens.

Any ideas from this productive and helpful group, will be appreciated or at
least food for thought!

Colin