Anyone managed to source/replace W211 variable displacement air-con compressor control valve?

[MJJ]

Hi all,

Diagnosing an intermittent air-con problem on my S211. When all is working, the air-conditioning is faultless, lovely and cold. This only lasts for maybe 20 minutes or so, then I get ambient air again. A little while later, without touching anything, and back to lovely cold air.

I get no fault codes using iCarSoft, and looking at the live data, it is obvious that the variable displacement compressor is only working some of the time. All the live data values make sense, but something is stopping the compressor duty cycle achieving what the climate ECU desires. A lot of searching is suggesting the electronic control valve, and that this is pretty common on the equivalent VW variable displacement compressors. There are no live data PIDs, nor fault codes, relating to the control valve for me to be completely sure. Removing the control valve to inspect means losing the refrigerant.

Mercedes don't sell the control valve separately, nor it seems do Denso. My belief is the compressor itself is good, as it performs well when the control valve lets the compressor compress. I also don't believe a failing mechanical compressor would be so digital (working perfectly, or completely off) in its operation.

Has anyone fixed similar, or found a place to source the control valve by any chance?

Martin.

Control valve is bottom right of this picture, with electrical lead going to it.

The valve itself is going to look like this, but it is very hard to be sure of part compatibility, and all I can find (supplier wise) are Chinese based companies who I have not heard of.

 

[MJJ]

Morning all,

I just thought I would post back on this one in case it helps anyone else with the same problem.

I found a US forum post that showed how the compressor solenoid could be purchased separately, and fixed the same problem for the owner of that car. I could not find a source for the solenoid I felt I could trust, so I decided to replace the whole compressor (which comes with a new solenoid) with a new Denso replacement (was around £260 from Autodoc). I replaced it (took a relaxed two hours, pretty simple if you move the power steering pump to one side), Kwik Fit gassed the system, and all has been working well for the last month.

Martin.