1955 heater vacuum valve open or closed

[zeroroadkill]

On my ‘55 there is a heater water valve which is controlled by a vacuum valve under the dash on the heater plenum. The vacuum line runs to the windshield wiper motor and tee’s off to the heater vacuum valve which is controlled by the dash heater temperature lever cable. When there is no vacuum to the heater water valve the valve is open letting hot water flow to the heater core. When vacuum is applied the heater water valve closes reducing the flow of hot water to the heater core. Moving the temperature lever to high moves the vacuum valve up which in my case let’s a small vacuum go to the water valve shutting the water valve down and when the temperature lever is put to low this moves the vacuum valve down shutting off the vacuum to the water valve. Backwards!!!
If I slide the temperature lever to high it gets cooler and if I move it to low it gets hotter!!!
What’s going on here??? Is the vacuum valve mounted upside down?

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[jack-in-sac]

That sure doesn't look like the heater valve in my '57. I am not entirely sure it is an actual OE part. Does it have a Ford part number?

 

[zeroroadkill]

Good point! No markings on it. I noticed it was mounted by the heater blower motor and not on the intake manifold too...
Found it online - generic. Probably works backwards from OEM!

Just ordered one that opens with a vacuum.

 

[Dick Rupp]

The vacuum valve is oem. The one under the hood is not. It is an aftermarket valve. The OEM fits on the intake manifold.

 

[Tater Salad]

Can someone please tell me. 55 vacuum heater valve. Is OEM open or closed with vacuum ?

Thebare, has your question been answered after merging your post with another?

 

[Dick Rupp]

The oem fits INTO the intake manifold. The aftermarket is fastened by the heater box. The OEM doesn't look anything like the picture on this article.

 

[Shawnski]

On my '56, the valve is located on the intake manifold. I noticed that there is vacuum getting to the valve, but no matter where I have the temperature lever, I always have hot air coming in. At idle I have vacuum at the valve with the heater controls set to OFF. The valve looks pretty new, could it be bad? How do they work?

 

[Ward 57]

Sounds like your control valve is leaking.

 

[zeroroadkill]

I remember when I replaced mine, which was relocated to the inner fender well by the previous owner, most replacement valves were NO not NC, The valve they used was NO (74603) I found the 74604 NC valve that worked.