I have a problem with my heater in my 1984 300SD. With the climate control **** at max I push the defrost button, or the front vent button, or any settings to make it blow, it blows cold air. OK that’s bad. But it some times blows hot air. It will blow hot air when the car is at idle (when it’s warming up in the morning, or at a stop light for a few min) it will blow hot air, but as soon as the car starts moving it blows cold air again. I don't understand why. Any one knows what the problem could be?

thanks

Nik

 

Sounds like a mono-value i dont know how to fix put part is cheap should be less than 50 bux cause mine was 40 and guy only took an hour to put it in. Would have tryed to do it myself but i cant work in the cold.