Heater always hot

[paulr]

Seriously, I ran out of ways to search this topic although I know there's a thread or two somewhere around here...

It's a minor one I've put off, but it needs to get done. My heater is always one temperature: hot. Now, the water valve is new, so that leaves the thermostat. Would running without a thermostat cause this effect? Don't look at me; it's another lovely P.O. 'improvement' that I'm getting around to restoring, but involves finding and reinstalling the missing surge tank that he also disappeared. Yeah.

My question about a missing thermostat is not found in the manual, naturally. Thanks,

Paul

[Tbird100636]

No. Without a thermostat or a stuck open one would cause the engine to be cold too long. A stuck closed thermostat would result in the engine to overheat. Is there vacuum to the water valve when set for hot but no vacuum when set for cold? If there is vacuum all the time it is a control head issue.

[tbird]

Paul the opening and closing of the vacuum operated water control valve is controlled by the bimetal control in the blower wheel housing the way I rmember it without getting out the books and reviewing the system.

[RedBird64]

I've got the same problem and have a non-AC car. I have to open the vent to get the temp under control.
I haven't had a chance to look into it yet though, still trying to get it to run right first before attacking the little things.

Scott

[tbird]

Scott
You do not have a heat control valve in a non air 64-66 the heater box control head and even the heater core is completely different, the water flows through the heater year round on them. The interior temperature is controlled with cable operated blend doors on non air your problem is likely that the foam seals are shot on the blend doors which is a major job to replace unless the heater box is already out on the bench.

[paulr]

Wow, lotta good help all at once. OK, I know my vacuum is solid since all those lines I did by hand with the dash off last year, and systematically tested it all during the re-installation. Now, I know that continuous vacuum to the water valve whether set to hot or cold is indicating control head problems. Here's the troublemaker:
Problem now is there's no manual instructions for trouble-shooting this guy. Any guidance? But, Jim's comment troubles me a little more:

Paul the opening and closing of the vacuum operated water control valve is controlled by the bimetal control in the blower wheel housing the way I rmember it without getting out the books and reviewing the system.

Jim, when I had my dash off, I recall contemplating the bimetal control and wondering what if any service should be rendered. Lacking knowledge, I limited my work to vacuum and heater core replacement, motor testing, resistor replacement, and put things back. Do you think I need to get back underneath again to get at this item?

Paul

[RedBird64]

Scott
You do not have a heat control valve in a non air 64-66 the heater box control head and even the heater core is completely different, the water flows through the heater year round on them. The interior temperature is controlled with cable operated blend doors on non air your problem is likely that the foam seals are shot on the blend doors which is a major job to replace unless the heater box is already out on the bench.

Ya, I knew about the different setup Jim. Your thoughts on the foam makes sense. Since I can hear the door moving that's about all thats left I suppose.
Oh well, at least it's stuck warm that way!
Thanks for your input.

Scott

[tbird]

Paul

A article is coming in the Scoop on rebuilding the control head I believe in the July issue Rene Gautron went through this when he was doing his 66 restoration. So as a follow up on the 3 part A/C feature Rene agreed to rebuild another one so I could document it for a Tech article. If you have the ports allowing or shutting off the vacuum at the right times the problem is in the control in the blower area and it can be removed by taking out the motor and blower wheel, if I had a bad control we would investigate rebuilding it for another instalment but the only one I have spare is a N.O.S. control so you know where that is staying.

[paulr]

Yeah, Jim that 3-part A/C series is essential for anyone (like me) who's rebuilding his A/C from the bottom up. I'm eagerly looking forward to Rene's piece on the control head.
So, I'm digging around this board and I come up with this: http://www.tbirdgarage.com/Site_2/Resto ... lve.html#0 which gets me excited, until I spy the cable attached to the end of the valve in the picture and the wind kinda goes out of my sails since I think that means this is valve is from a non-A/C car, right? Also, this piece documents the '63, and I have a '64. Jim W., I already wrote this in a PM to you, but then I thought further that the info might be good for the folks, generally. Would the heater valve I'm questioning be different between AC and non-AC cars? Or, to make this even more messy, is this like the valve that Scott (RedBird64) has on his '64? Many thanks,

Paul

[tbird]

Paul
The 61/63 heater and A/C is totally different from the 64 / 65 systems, the same water control valve is used on both A/C and non A/C cars.

The 64/66 models only used vacuum controlled blend doors and water control valve on the A/C models, heat only cars used manual cable controlled
doors and allowed the water to flow through the heater core at all times (the core is completely different between A/C and heat only cars) using the cable controls to divert, mix and shut off air flow as the control head manual cables are operated (yes even the control head is different no Vacuum to it on heat only). Off the top of my head I can't think of any part of the system that is the same between A/C and heat only cars.

Edit It just hit me what part is the same on A/C and heat only cars, they both use the same heater motor switch which also has contacts in it to energize the A/C compressor, the wiring harness and plug for A/C cars is different and connects to the extra contact in the switch

[Sierra John]

Paul,

I went through the same thing with the control head on my 66 last year. I discovered that several of the ports were clogged. I ended up using a needle to dislodge the decades of crud. Once all the ports were open, my AC/heat has been working great. Good luck.

[66T-Bird]

what does Control Head exactly mean in this feed i'am lost

[tbird]

Skip

The a/c 64-66 Tbirds have a vacuum control rotary circular valve which selects different ports for the control vacuum to open dampers, blend doors, and the water control valve only on a/c equipped cars. The cars with heat only control everything with cable operated dampers and blend door.

Was going to post a picture of NOS vacuum control head and the temperature control mounted in the blower area on a/c cars but for some reason my computer will not cooperate tonight for some reason.

[66T-Bird]

Jim thanks for the reply and once that computer decides to cooperate please send pics if possible

[Terry64HT]

It may not be relevant, but there is another source of heat, especially at the driver's feet that some confuse with the heater duct. There is an inspection plate for the transmission located high on the trans hump near the accelerator. It is often not reinstalled by mechanics. If not there, the hole will dump an unbelievable amount of heat to the foot area.
Terry
64HT