W212 Climate Control Panel intermittently dead

[REBIS]

These cold days I have noticed that when I start my E220 more often than not the Climate Control panel is dead and after about 15 seconds the engine cooling fan will start up. The climate control panel will remain like this for varying lenghts of time and during this time the engine fan will remain running. After a while the Climate Control panel will spring back to life and work properly and the engine fan will stop running. On other occassions the control panel and fan will behave correctly from startup and sometime after the control panel will die and the engine fan will start up.
This to me sounds like a bad joint somewhere in the electrics, I've noticed that if the control panel is dead I can tap the top of the fuse panel with the cover removed with the palm of my hand and all will come good. I have replaced fuse 12 in the front SAM (maybe a joint problem) but this did not rectify the fault.
I was wondering if I could remove the SAM to look at the connectors on the underside, I do not know which of the connectors to look for as I cannot find a wiring diagram anywhere for the car, there could also be a failing relay in the SAM used by the Climate controls.
Can anybody help?

 

[DarloDave72]

Hi Rebis, I had exactly the same issue on my GLC, mine was traced to a chafed wire in the driver foot well where the wiring had been incorrectly routed, but it is common for the pressure sensor on the a/c condenser to be at fault (I don't believe this part is particularly expensive or difficult to replace).

 

[REBIS]

Hi Rebis, I had exactly the same issue on my GLC, mine was traced to a chafed wire in the driver foot well where the wiring had been incorrectly routed, but it is common for the pressure sensor on the a/c condenser to be at fault (I don't believe this part is particularly expensive or difficult to replace).

Hi DarloDave,
Thanks for your reply, I will attach the OBD11 to the car tomorrow to see if I can get a pressure reading to see if it needs replacing.

 

[REBIS]

Got an AC pressure sensor reading but the climate control panel was working the pressure was 4.5bar, but I don't think this is the problem, having had a rethink the climate control panel when working normally lights up when the car is unlocked using the key fob, when the car is in the fault condition the panel does not light up unlocking with the key fob no mechanical influence at all. This must mean an electrical fault and if tapping the front SAM brings the climate control panel back to life then the fault must surely lie there.
Anybody out there know what the problems are repairing / replacing the front SAM or had any experience just removing it.

 

[Uky]

If the engine cooling fan looses the CAN-bus connection with the engine controller (and the engine temperature) it starts and runs at highest speed in order to prevent engine failure due to (possible) high temperature. So there is some communication problem. I would start looking at every possible bad connector/connection point. The cable harnesses are manufactured in low-cost countries and there has been several cases of bad crimped elements in the connector housings. It is sometimes difficult and time consuming to find. There are also other possible causes: Mercedes uses junctions inside the cable harnesses and these has been known to be "less than perfect". You will have to unplug the connectors and carefully also look for misaligned contact elements.

 

[lalmon]

Hi Friends,
I have the same problem of Radiator fan running on full speed when I start the car and the climate control unit is fully dead on my 2010 model E-class W212 200 CGI. Everything else seems working normal. Can you any expert here help me.

Thanks
Lalmon

 

[lalmon]

guys, mine is traced to a faulty climate control module. Service center guys pluged a spare one and everyhing starts working normal...

 

[MrGreedy]

Thank you for updating us. Mich appreciated to get a fix confirmed