Air con voltage to compressor - why down?

[John Plum]

OK the question as per title - the problem on my Xantia II Hdi 110, I have no power going to the compressor when AC switch is on and lit, low speed fans are whizzing round and blower is on and working at variable speeds.
What could be the cause?
Thanks for insight!
John

Ps I just Changed the compressor unit and its tested with direct feed, when it switches on.

[John Plum]

Thought I could add:
The 'fault' was found at the aircon gas recharge station, so the young bloke, hesitantly advised me mot to recharge it now, as 'he wouldnt be able to determine how much gas pressure he would be adding. '
But, perhaps the fact that it has no pressure in the system, due to compressor refit, means there will be no power sent by the pressure switch?

[MJM]

If the system has no refrigerant in it then the low pressure switch will inhibit the compressor clutch.
I don't know how long you had the system open to atmosphere for but it is usual practice to change the drier when the system has been opened.

[Hell Razor5543]

I would be inclined to ask DickieG about this. He knows about aircon, and probably more than most people at recharge stations.

[John Plum]

Thanks, I've asked Dickie for his help.

In answer,
- the compressor swap was done within 24 hours.

Although the gas is more or less empty, I think there is an electrical fault, from the results of testing pressure switch.

Pressure switch tests:
------------------------------
With pressure switch disconnected, AC switch on, engine running:

Test 1) 12 volt power at feed plug terminals 2 and 4.

Test 2) shorting pins 3 and 4 - causes fans to shift to high speed (correct)

Test 3) shorting pins one and two did not cause compressor clutch to run (fault indicated), although the compressor known to work with direct power feed


- Fault could be a relay somewhere or, reading from ECU? (Note, This, being an hdi, is a case where the ECU controls aircon, not the citron).

Probably time for a Lexia session.

Is there a kind soul in West London with Lexia on offer?

Cheers, john

[DickieG]

PM just sent.