Is there a way to test the actual climate control unit? I cannot get the heat to turn off in my 1985 190e no matter what I do. Does not matter what temperature I set it at or which of the buttons is pushed. Nothing but heat. Before I spring for a new climate control unit I would like to perform some tests on it. Looks like it probably could be tested with an VOM, but I do not know for sure. Thanks for any help.