I've been looking at the Citroen wiring diagram for the factory-fitted AC system, in preparation for getting the system on to R134a in the new year.
Apart from needing gas, the system appears to be operational, with both radiator fans firing up as soon as the dash slide control is moved away from Off. There's also very faint warmth at the top pipes of the condenser, so it looks as if the compressor is attempting something, when switched on very briefly; good signs.
My problem is fully understanding the Citroen circuit diagram:
.
↓ click to enlarge .
↑↑ The radiator cooling fan part is straightforward enough - two-stage thermo-switch, operating the usual 3 relays, to put the fans into series (slow) or parallel (fast) running.
It's the action of the dash slide control I'm not clear on:
. ↑↑ EDIT: Diagram labelling now revised - see post below ↓↓
.
The diagram shows the switch with 4 positions, and a 2-pole ganged arrangement (A, B).
On the diagram, the right-hand position I take as Off, for both A and B. Have called this Position 1.
Then it gets interesting:
In Position 2, A also connects to nowhere, but B runs to Gnd, so switches on Relay 742, which activates the compressor. It also switches on Relay 733, which puts the fans into Slow speed (similar to the low-temp thermo-switch operating). OK, as expected so far.
In Position 3, B remains grounded (compressor continues to run), but A switches to Gnd, thus putting the radiator fans into High speed. Is this correct?
For Position 4, A keeps the fans in High speed, but B switches to nowhere, so seemingly cutting the compressor (and the Slow speed connection, over-ridden by the High speed running).
What is the function of Position 4 ?
Also, the action of the dash AC slide control is (on the one here anyway) without detents, just a continuous travel across. I'm not clear exactly how it might cleverly operate
