Help!! My defroster is stuck on defroster.
My '96 cummins is stuck on defroster. The fan works fine as does the tempature control. But the selector switch will only go off or defrost.If Iturn it to the other positions it still comes out the defrost. I replaced the switch to no avail.I tried to find the source for the vacuum but couldn't. My Ford buddy said the diesel dosen't supply enough vacuum so there is a pump. Is that true?Any ideas? Thanks