Does anyone know where the vacume tube from HVAC controls in the dash that goes to the heater core bypass valve underhood, Exit the fire or how it runs underhood. Pictures would be great. The car I just bought has this unhooked so the heat dosent work and its rather cold. Thanks for the help.

 

The heater core bypass valve defaults to sending coolant through the heater core (no vacuum to the valve = coolant flowing through the heater core). It only gets vacuum sent to it when you push the hot/cold selector all the way to COLD, then it diverts the coolant through the bypass line.

I haven't traced it all the way under the dash but I believe it runs inside the main wiring loom that loops over the back of the engine and it pops out of that loom near the tranny dipstick, going a basically straight shot to the heater bypass valve. It's a small dimameter plastic hard line and only has a rubber end on it right where it plugs on the hose nipple for the bypass valve.