Hello all! I have a 1989 535i with a good aux fan, ice cold r134 conversion and I believe a good heater core. However, yesterday, the left set of vents only started blowing hot air whilst the others blew nice cold air- I fiddled with the left temp control up and down for a while, but no luck. Anyway, after a few hours, she blew cold again. Is the dial itself bad, or is there a sticking valve in the heater core? Thanks!
Chris