I'm having an issue with my 85 300sd where the blower shuts off if you move the temp control past min. It will blow if it is on min but nothing past that. Defroster won't blow either. I can feel heat coming out. I was thinking maybe monoclave valve but wanted to see if anyone had any other ideas. Checked and replaced the fuses. I can get it to come on randomly once in a while but Sunday night it stopped working again. Any ideas are appreciated.