Originally Posted by MichiganLarry
My 2002 F-350 diesel has developed a new quirk. Since yesterday it wont switch from defrosters to heat. The air coming out of the defrosters is plenty warm but the floorboards are getting pretty cold on my 45 minute drive into work. Any ideas?
Check the electronic vacuum pump on the passenger side of the engine compartment next to the vacuum reservoir. They go bad all the time.