garyfish340
Well-Known Member
I have a 1975 Plymouth Duster that had a slant 6, automatic, w/air. In the photo is a vacuum actuated heater control valve that seems in good condition. My question is, what exactly does it do ? I'm fairly certain that the gen III hemi ( without air ) I've installed doesn't have a bypass hose ( so to speak), unless it's internal on the water pump/timing chain/accessory cover. My 1971 Cuda had a bypass valve that was cable operated, and had a tube that crossed over to the return hose. This is just a single hose with a vacuum valve, and the vacuum system. Also the vents inside the car hang from the bottom of the dash, and the cowl box is only on the passenger side end of the cowl. I'm guessing the vacuum hoses that go from the heater control valve, through the firewall probably operate the vent doors under the dash like a GM car. (When my dad picked up his 1973 Duster new, it had a totally different system than this one hanging below the dash, there were vents under the part of the dash by the headlight switch, and under the glove box, by the door jambs, the rest may have been the same. but it's all unfamiliar to me.) I need heat, and defrost. Any answers ? Thanx...