Citroen C4 AirCon

[Daibach]

Hi Xantia, I can get the pressures checked at my local garage, since they do aircon refills and did a very good job on my previous Focus. The system might have been regassed in Feb although I did not ask for it to be done, when I bought the car ( if you believe the salesman, personally from other problems I have had with the car, I would not). I did not check it then, but I got it redone at ATS in June since it was not as I had expected ( suffice to say that sums up the story of the car's supposed pre sale preparation). So, I think there is a high likelihood of a leak in the system, as you suggest. I will ask my garage if they can do the luminous dye test. Any ideas why the clutch would be permanently engaged and also any ideas how to free it off? Needless to say, it's at the most awkward part of the engine to reach ( unless the French have very long arms?). I have tried a random spray of WD40 and a gentle tap with a hammer, but to no avail. By the way, I confirmed the fact that it and the end of the centre shaft were spinning by marking with a chalk line across the face of the clutch and also on the shaft when stationary and neither of which could be seen when the engine is running, in car aircon switch being either on or off.

[xantia_v6]

Are you saying that the compressor is engaged with the A/C switched off?

I am assuming that there is just enough gas in the system for the compressor to engage, but not enough to have any significant cooling effect.
You could loot at the A/C components, especially the condenser and pipes going to it, as a leak usually leaves an oily residue that attracts dust and grime.

[PaulC5]

You might find your local garage uses pressure gauges to check the refrigerant pressures but you need a diagnostic check to see what the car thinks the pressures are.

If you post up your VIN admin might look up your oil filter to see if the parts diagrams show any electrical connector to your oil filter cover.

[Daibach]

Thanks once again Paul C. I had not thought about what the car might be thinking....I am of the generation that " anything can be fixed with a 1/2" spanner and a screwdriver", and to be honest, usually could
I'll go into the part no. thread and ask the question about the mystery oil filter cover ( if indeed that's what it is)

[Daibach]

Hi Xantia, Yes the compressor clutch is engaged all the time. I leave the aircon switched on all the time, to hopefully prevent any possible damage. The compressor on the car has part no. 9676862380 on a sticker with the Citroen logo and looks like it's been there for ever. Marc tells me there is an upgrade part no. to this , so I assume the units are interchangeable. Looking at potential replacements, they all seem to have a single black electrics socket underneath at the end opposite the pulley but no separate yellow socket for the clutch, which is referred to on other models of compressor, and I can only see one wiring harness going to the existing compressor. Have you any experience of this type of set up?

[GiveMeABreak]

Compressor Wiring



8020: Air Conditioning Compressor

Wiring
8068B: Control +CPT3
8058B: Compressor Valve Control

Location

[Daibach]

Thanks marc. So does this suggest that there isn't a clutch as such and the compressor is designed to rotate all the time, with the a/c operation controlled simply by an internal pressure relief valve, taking it's sensing from the pressure switch in the HP line? Or have I got myself totally confused here?

[GiveMeABreak]

Correct, this is a clutchless system. You also have 'Simple Air Conditioning' which means you manually switch it on or off on the control panel.

Here's the internals for operation:

(2) Compressor shaft.
(3) Oscillating plate.
(4) Piston.
(5) External control valve.
(6) No. cylinder.
(7) Clutchless pulley.
The clutchless pulley (7) is driven by the engine accessories belt.

When the air conditioning cuts in, the external control valve (5) permits modification of the pressure inside the body of the air conditioning compressor according to the temperature required by the passengers.
The modification of the pressure inside the compressor body has the effect of tilting the oscillating plate (3) so modifying the travel of the pistons (4).
The longer the travel of the pistons the greater the volume of fluid to be compressed, therefore the flow of refrigerant in the loop will increase in turn increasing the production of cold air.
When the air conditioning is switched off, the pressure inside the body of the air conditioning compressor is modified to allow the oscillating plate (3) to return to the position perpendicular to the air conditioning compressor shaft (2).

N.B.: When the oscillating plate (3) is perpendicular to the compressor shaft (2) the travel of the pistons (4) is equivalent to approximately 2% of the maximum capacity. When the air conditioning is not activated, the compressor continues to be driven by the ancillary drive belt.

Compressor protection
The compressor is connected to the accessories belt of the engine, that is fitted with a protective device in the clutchless pulley (7).

If the compressor jams, the force resulting from the drive of the clutchless pulley (7) by the accessories belt destroys the mechanical fuses thus freeing the pulley without clutch (7) from the shaft of the compressor (2).

[Daibach]

Thanks due once again to you Marc. I think my next exercise will be to get the HP valve checked and replaced if necessary, then to get the system checked for leaks.

[citroenguy]

Unless you have proof that the AC held the correct amount of refrigirant from the beginning, this sounds like they didn't pressure test it. And the refrigirant has leaked out again..

Hm, i had a look in service data and the EP6C doesn't have a clutch type compressor. Instead it has the slightly more modern variable stroke type. I e it spins all the time and when it is off the stroke is zero (it is a piston pump)

[Daibach]

Thanks for that info Citroenguy. I made the mistake of using ATS instead of my usual garage, because of a special offer voucher. I think I know now why they had the special offer!!

[Daibach]

I should have asked the question " does anybody know if you can replace the aircon hp switch without losing all the gas in the system. " I would really like to hope there is a Schrader valve in the threaded connection on the pipe . Also there's lots of these 3 pin switches on Ebay, will any one fit my car or do I need to know the OE part no.? Thanks.