I have a longish tale of woe on my S Class w221, 320 CDI. It's a 2006 car with 85k miles under it's belt. I had an issue about 18 months ago with the car. I had just been a 15 mile journey when the car stuttered and felt like it was about to stall, very shortly afterwards the air con started to hiss loudly. I booked it in to the dealer who told me it needed a top up but it held a vacuum and showed no errors on Star. They also added some dye.
All was well for another 8 or 9 months then the same thing happened, I had a look round and couldn't see any dye except small traces around the valves which looked like it was there from the top up. I also replaced the temp sensor in the condenser as I had been told this could sometimes make the air-con turn itself down, made no difference. I took it to Halfords this time who had a special offer on. They too confirmed it passed all their tests. They topped it up and added more dye.
Roll on to a couple of weeks ago and the same thing happened a third time. Just driven about 8 miles from cold, engine stuttered like it was going to stop and the air con started to hiss. This time I stripped away all the wheel arch trim and under panels and followed every pipe until it went into the cabin. Not a trace of dye anywhere.
This time, unlike previous times, the Air-Con wouldn't switch on, the 'tick' disappeared for 2 seconds then came back on. I took it back to Halfords who once again confirmed it passed all their tests despite leaving it on vacuum longer. They topped it up again but the Air-Con tick does the same, disappears for 2 seconds and comes back on.
I am loathed to put it into MB for another expensive go on Star to be told there's nothing showing and would I like to part with £2k for a new compressor and drier just in case?
Has anyone else experienced this issue with their AC and if show what was the cause?
To me, without knowing what features the compressor has, it looks like the system thinks there is too much pressure ( or there is too much ) and dumps it's contents through a PRV which lets the engine ingest the refrigerant hence the choking. I have tried unplugging the pressure sensor near the dryer but that made no difference.
Does anyone know of a way to reset the AC? I've tried holding the 'ON' button which resets flaps and sets temp to 22 degrees but AC still won't go on.
Sorry it's a long winded post and it's in the Engine section as it looked like the most logical place to put it. Thanks for reading.
Robert
All was well for another 8 or 9 months then the same thing happened, I had a look round and couldn't see any dye except small traces around the valves which looked like it was there from the top up. I also replaced the temp sensor in the condenser as I had been told this could sometimes make the air-con turn itself down, made no difference. I took it to Halfords this time who had a special offer on. They too confirmed it passed all their tests. They topped it up and added more dye.
Roll on to a couple of weeks ago and the same thing happened a third time. Just driven about 8 miles from cold, engine stuttered like it was going to stop and the air con started to hiss. This time I stripped away all the wheel arch trim and under panels and followed every pipe until it went into the cabin. Not a trace of dye anywhere.
This time, unlike previous times, the Air-Con wouldn't switch on, the 'tick' disappeared for 2 seconds then came back on. I took it back to Halfords who once again confirmed it passed all their tests despite leaving it on vacuum longer. They topped it up again but the Air-Con tick does the same, disappears for 2 seconds and comes back on.
I am loathed to put it into MB for another expensive go on Star to be told there's nothing showing and would I like to part with £2k for a new compressor and drier just in case?
Has anyone else experienced this issue with their AC and if show what was the cause?
To me, without knowing what features the compressor has, it looks like the system thinks there is too much pressure ( or there is too much ) and dumps it's contents through a PRV which lets the engine ingest the refrigerant hence the choking. I have tried unplugging the pressure sensor near the dryer but that made no difference.
Does anyone know of a way to reset the AC? I've tried holding the 'ON' button which resets flaps and sets temp to 22 degrees but AC still won't go on.
Sorry it's a long winded post and it's in the Engine section as it looked like the most logical place to put it. Thanks for reading.
Robert
