26fastfreddy
New Member
I'm looking for a vacuum diagram for a/c heater controls, the valve assy is the 5 push button style # 3431020
There were many part numbers applied to those 5-button switches, and they interchange. Whichever one you have bought will work in your car once you sort out the vacuum hose routing correctly. The diagram you need is in the FSM, chapter 24. Your type of factory air system was used from '65-'72. The heater water valve through '70 had two vacuum hoses going to it: one to open the valve and one to close it. The water valve for '71 and '72 had one vacuum hose; it was spring-loaded rather than having the "other side" vacuum hose. This didn't (and doesn't) necessitate a different switch, just different hose configurations. Once you go through, hose by hose, and make sure vacuum goes (and doesn't go) to where it should (and shouldn't) be in every button position, your system will work correctly. It's tedious to figure out, and while you're in the middle of it it seems like it'll never work correctly, but keep at it, and it will.
Glad to help out. I mention the heater water valve because the pre-'71 type has been unavailable for years, or very expensive when you can find one, so often the earlier cars have been repaired somewhen along the line with a later-type (single vacuum hose) valve -- this, by the way, is a repair I'm completely onside with. Anyhow, if you find a single-hose valve, you'll have to deviate from the factory vacuum diagram to get everything working right.
Use this one for cars with 5/8" heater hose, or this one for cars with 1/2" heater hose. Most of the '70-'72 cars have 1/2" on the inlet side of the heater; pre-'70 and post-'72 cars mostly have 5/8""] for cars with 1/2" heater hose. Most of the '70-'72 cars have 1/2" on the inlet side of the heater; pre-'70 and post-'72 cars mostly have 5/8"