SLK 250 heater controls

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New Member
Jan 4, 2021
SLK 250
I have a 2012 SLK 250 and the heater/climate controls including blower and heated rear screen are all unresponsive and not lighting up. The main engine fan is also spinning at max when the engine is running. I scanned the car and the following codes came up. I have checked the fuses in the nearside of the engine compartment and all are okay. Has anyone else had any issues like this or advice to offer on how best to proceed?

Screenshot_20210104-115515 mercedes r172.jpgScreenshot_20210104-115443 r172.jpg
I can tell you that if you run the car without the heater controls plugged in, the cooling fan will run at max speed. I had to move my car with that unit not fitted and was initially surprised to find it felt the need for the cooling fan in February on a cold engine. I assume it is to do with the AC condenser as it may well not be able to turn off the AC if the HVAC controls aren't operating.

So from that, I would deduce that you have either a faulty connection to your controls or that they are faulty themselves but I wouldn't panic about the cooling fan. I'd offer you my spare CLK heater controls as a test but you couldn't be much less local to me (and I expect they are different anyway). I'd start by removing them and checking/reconnecting them. You could try the reset/normalise flaps procedure if that is a thing on a later SLK, I doubt it will cure it but it's free to try. For the CLK and earlier cars than yours:

To reset the unit hold down the demist and recirculation buttons for > 5 seconds, if successful both LEDs flash and the unit will cycle the flap motors to normalise their position.

Clutching at straws probably though.

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