Quote:
Originally Posted by 71CHEVYSHORTBED402
Yes...........
Old thread but a good one. I'm working on a 1971 with a three port control valve, which I really scratched my head over #3 running to the water valve. After checking my water valve(s) today it's because it doesn't work 
#3 opens vacuum when the controller is set to outside defrost (de-ice) which closes the A/C water valves I've used since? doing the opposite what it's supposed to do.
My guess is factory was using up old stock and plugged #3. Can't swear to it, I chucked the old F/W grommet, the hoses were mostly gone, though I'm 99/1 the water valve is correct.
So yeah, the above diagram for the old three port / water valves opens the valve, it's counter-intuitive, at least to me, but maybe that's why they changed them 
|
As explained in your other thread the three port uses the normally closed water valve. Typically the one with the mounting bracket. All vendors I have seen it seems to be the way the replacement valve are described. 71-72 would have came with the bracket type valve from factory. Of course you could plug the #3 port and plumb like a 2 port but would then use a normally open valve without the bracket.