W211 Air Con Select Button

[Harry]

I recently noticed that when i go to switch the air con button on, on my W211, instead of the red LED going off, it flashes on and off for a few seconds then stays on permanently. In other words, it remains in Economy mode.

I thought that this was perhaps this was due to the cold weather not allowing A/C to be switched on if outside temp is low.

Maybe its me missing something here, if anyone can shed light that would be much appreciated, thanks, Harry

 

[splang]

erm, I don't think it's that. Doesn't happen on mine.

Sorry I can't suggest what it is. I don't think it is the duovalve ( a common problem) as mine didn't do this when the valve was on the blink.


Good luck in finding the answer.

S

 

[RichardM]

If you press does the econ/aircon light stay on? If yes it sounds like you'll need a trip to the dealer.

 

[davidH]

Just checked mine out whilst on a short run. The red light is normally off in full auto thermatic mode. When I pressed the aircon button after about a mile the red light came on without any flashing and there was cold air coming from the vents because the heater booster was switched off ( see pages 177 and 191 of hand book). If this happens to you then it would suggest a faulty switch but perhaps someone more technically minded could advise better. Either way it is definately worth taking it in to be checked out assuming its under warranty.

 

[jaymanek]

I recently noticed that when i go to switch the air con button on, on my W211, instead of the red LED going off, it flashes on and off for a few seconds then stays on permanently. In other words, it remains in Economy mode.

That means there is a problem in the system and its shutting itself down... need to get it checked.

 

[Harry]

It will not let you put it in the mode where the A/C red light is off. So, when i switch on heating/cooling system red light on meaning economy mode. If i select the A/C button to switch into A/C mode thus switching red light off, instead it flashes about four times then remains on.

Basically, its not wanting to go out.

I guess a trip to the stealer is required. Was hoping someone else might have noticed this happen before. I rarely use the A/C and actually pressed it by mistake when i noticed it flash and realised that something was up.

Thanks for the help though, i'll let you all know what i find out.

 

[Harry]

PS, It runs in economy mode fine so still works to control temp at whatever its set at but it means i can ONLY run in economy mode as apposed to A/C mode.

 

[prprandall51]

Hi Harry, you do not want to leave your aircon off for an extended period - the seals in the system are lubricated by oil in the compressor gas. If you don't run the A/C at least once a week for 20 minutes the seals can break down and allow the system to de-pressurise.

This is true of all A/C equipped cars, not just MB.

A complete lack of use may be the reason why your system has failed. There is a pressure switch in the system that will not allow the compressor to fire up unless there is sufficient pressure in the A/C system.

Philip

 

[Harry]

Hi, thanks for this information. On occassions i have left my car on the drive for 1-2 weeks and used my wife's car so i have definately not used the A/C for these periods and especially during the colder months i did not have it on as i tended to use it primarily for the cooling aspect rather than the boost heater.

How would i know if this really is the problem and secondly is it expensive?

Harry

 

[prprandall51]

The dealer will tell you if this is the problem. It may not be too expensive. Sometimes, systems can simply be re-gassed and all is well again. If the gas just leaks out again, they put a special dye in the system and trace the leak that way.

If the car is under warranty then you should have no problems, I would imagine. Best not mention that you have been leaving the A/C switched off for long periods of time though..... A week or two or even a month or so is fine but longer periods might be bad news for the system. Plenty of cars stand around on forecourts for longer than that while waiting to be sold and they don't appear to suffer.

If the repair isn't covered (though I cannot see why it would not be) then there are plenty of good quality independent A/C vehicle specialists who will fix the problem cheaper than the dealer will.

Philip

 

[jaymanek]

Hi, thanks for this information. On occassions i have left my car on the drive for 1-2 weeks and used my wife's car so i have definately not used the A/C for these periods and especially during the colder months i did not have it on as i tended to use it primarily for the cooling aspect rather than the boost heater.

How would i know if this really is the problem and secondly is it expensive?

Harry

Its very likely to be.. What you need to hope for is that a simple regas is all it needs... Condensors will be very expensive on a W211...