Hello, I am working on a 66 bird with a/c and have no vacuum to heater valve in any selector position. I cannot find the thermal water valve control switch that I see in diagrams. Is it hard to get to? Is there another way to hook controled vacuum to the valve that does not require removing the dash? Not even sure if thats the problem, all I know is that there is no vacuum to water valve in heater position. All vacuum lines are hooked up at control head. Any help would be great! Thank you!

Have you checked the vacuum line at the valve, and are all the vacuum lines hooked up correctly?

The thermal control is accessed by removing the blower motor and reaching in through the hole.

I would first make certain that the vacuum lines are correct under the hood.........

There are 3 vacuum hoses that go through the firewall right under the vacuum can.

The large hose goes to the center nipple on the vacuum can

The other larger size hose goes to the water valve

This leaves 3 hoses that tee into the vacuum supply line.
1. The small hose under the can, 2. the hose that comes from down low on the firewall of the passenger compartment, 3. the hose that comes from the A/C vacuum can that is under the front RH fender.

Here is how to connect these 3 remaining hoses....

Connect a 7/32 hose to outside nipple of vacuum can

Tee off 7/32 hose to nipple of 66 AC vacuum can under the front fender by the battery. there is only one nipple on the bottom of the can

Tee off 7/64 hose to small hose that comes from firewall under vacuum can (this line activates the A/C clutch switch)

Tee off 5/32 hose and hook to vacuum hose that enters firewall by the fuse panel (this vacuum hose is for the trunk locks, rear vents and emergency brake)

Place check valve in the line
Connect 7/32 hose to vacuum port on engine manifold

This message has been edited. Last edited by: Jim 66Tbird,

Thank you for the info Jim, I will see what I can come up with!