O.K., I don't get it! Are they tied into the doors, meaning, if you open and close them to many times once the heaters are on, it shuts them off? Many times I've started up on a cold morn and turned on the heaters, go back in, forgetting something, next thing I notice they're OFF! Anyone have a clue?

Faulty drivers door module. This seems to be a fairly common problem.

Thanks Max. Guess I'll have to have service look at it next time it's in.