1983 500 SL Heat will not shut off
 

I have the above mentioned Mercedes. I had as situation a few years ago where the heat would not turn off. I went to look at the heater control valve and unplugged it and pluggedit back in, and everything worked okay.

Well I think that I have run out of luck as I tried that yesterday and that did not work. So at this point I need to determine where the problem is. Is it the switch, heater control valve, vaccume line or?

Any ideas on this? Thanks, Nick

Which climate control system do you have?

It has the automatic climate control. It has the roller on the left to control the temp and the two fan settings with the auto buttion between them.

That should be the ACC III system.

Easiest recommendation would be to install a monovalve repair kit.

all heat all the time is defult for bad ACC control unit or bad monovalve . I would start as mentioned with Monovalve

Okay sounds good. I was hopeing to find a sure way to diagnose wich componet is bad, but it sounds like the consenes in is on the Mono Valve.