I could use some help on this one. Just purchased a 77' 300D, the a/c doesn't work, but not worried about that yet. The climate controll only puts out heat. I can select hi and low auto, bi level and defrost just fine. It just won't blow cool outside air.
I first thought the Mono Valve, but turns out the 77' system doesn't have one. Can't find any info about non-mono valve systems. I am wondering if it is a problem with a "hot/cold air mix valve" or something else. I don't know how the system works.
Any hints on trouble shooting a non-mono valve system would be great!