many thanks for the input, do you think it could be resolved by a straight swap out of unit or is the temperature in the cabin is not being regulated properly ?
I have found a local company who have agreed to check the circuit board / components, with the possibility of re-soldering all joints to eliminate dry joint failure.
will keep the forum informed.
however - if anyone else can add input - the more the merrier !!!!
many thanks to all
1990 300SL 24v
remember - "if you dont ask - you don't get" and
"its easier to get a pardon than permission from your partner"