I have seen this problem around the forum and no one has seemed to come across a real fix. I think this is the true fix for it.

https://www.benzworld.org/threads/w2...bulbs.2141945/

On my Crossfire, the blower speed would change speeds by itself and even turn on when it was set to venting only, where the blower and A/C light should be off. I already replaced the blower resistor and it did not make a difference.

I tired the fix myself. I desoldered the potentiometer and soaked it in isopropyl alcohol. I also separated the metal backing and plastic slightly using a pocket knife to make sure the alcohol got inside. I turned the **** to clean inside and thoroughly dried the part before resoldering it. Now the blower speed seems to work normally.

There may be a way to remove the temperature wheels so you do not have to desolder the poteniometers for the temp wheels to get to the blower potentiometer, but using an allen key on them did not work for me. It may mess something up if you force it. My wild guess is that the white plastic with the allen key hole is a shaft that snaps in when assembled. I do not see why it would fit an allen key in that case though.

A new potentiometer would be better than cleaning but I am not sure if they are available. The brand is Piher and there is an "X" on the bottom of the front side. The number stamped on the side is 4k7344ME.

Hope this helps someone!