W205 AirCon issue
 

I have a C220 W205. The aircon has failed. The clutch for the compressor does not engage. (I have checked the solenoid part by putting 12V across terminals and clutch will pull in). So what is stopping it running? I understand low gas pressure can be the cause. I have a pressure gauge arriving soon to check. Also I believe the pressure switch can be at fault. Any way of checking pressure switch / sensor and where is it? Possibly the control module is faulty, again any way of checking and where is it? Or is there something else to check?
There is something else, not sure how relevant but initially a while ago when first noticed the A/C wasn't cooling, the A/C indicator light didn't light when flicking A/C switch for on most times...But it does light every time now when I try with futile hope to turn on the A/C.

Fixed ?
 

Hello, can I know what was the problem finally ? Thank you.

Hi, Yes it was simple. Only lack of gas. I bought a gauge and saw there was nearly no pressure, bought some gas and put it is. Compressor started working and A/C ok. That was back then. Gas was down a bit this summer but only just at minimum pressure, put some more in from same bottle. Must have a very slow leak but good enough.
Now a bigger issue with NOX sensors!!!!!

Thank you for the reply !

But I do not understand why your compressor stopped working ? I have a small leak to fix and I refilled gas twice this year, but even empty (or almost empty) it seems that my compressor is always working ? Am I wrong ?

Well, I saw on the forum, low gas pressure prevents compressor being clutched in. Partly why I decided it was likely to be a pressure issue. My gas was nearly gone, just a very slight pressure above zero on the gauge. Generally they say not to put in gas then probably as you can have a large gas leak and lose it I suppose but I could see some pressure, therefore the system didn't have a big hole. The previous year 2020 we didn't really need the A/C lockdown I suppose and also we live in Scotland, so didn't bother to much when it looked like the system was faulty. Sometimes the A/C light came on sometimes not but there was no cooling. Anyway I put the gas in, in July 2021 and the compressor started quite soon, it was still well below minimum pressure when the compressor started I think. The gas stayed so no major leak although it was back towards minimum operating pressure this year when I checked in May.