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Heater Water Flow Valve On Factory AC Car

67GTX440

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While removing the heat/AC box from under the dash to replace a leaking evaporator, it was
noted that the copper wire looking connector that runs from the bottom of the heat/AC box to the water valve in the firewall was snapped off from the water valve. (See pictures.) I called Classic Air who had rebuilt my heat/AC box to ask about the function of this probe and although they could not really explain the function rather than to somehow regulate flow to the heater core. They said it was a somewhat unnecessary part as water flow open or closed was regulated by the cold/hot lever on the heater control that manually opens or closes the water valve to the heater core and if they rebuild a heat/AC unit where the probe was damaged they just crimp it off. Not sure of the copper piece is actually solid or hollow inside and how it transfers a heat reading. They said this part not being replaced would not interfere with the working of the AC or the heat. Still, it would seem to have had some original function.

Can anyone explain what the probe running to this valve was designed to do? Is it supposed to close the manual valve somehow if it fails?

The guy at Classic Air also said this part is "unobtainium" from any aftermarket source and if you needed one you were pretty much stuck with buying one used that would probably need rebuilt. Classic Air does rebuild them if they are intact.

If I put things back together without this, should I just go ahead and remove the probe end from the heat/AC box and does it need to be pinched off where it is broken at the valve at the top?
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Capillary tube to regulate freon flow to prevent evap. freeze up. Need new expansion valve assy.
 
Heater Control Valve.jpg
The part I am talking about is the one shown in this link from the Classis Air web site. They refer to it as a heater valve. They still do not explain its function very well. Could it be a probe that causes the heater flow to activate slightly if the evaporator begins to freeze up? The probe on the end of it runs to the heat/AC box. I thought the expansion valve was on the firewall side and has the probe that is attached to one of the AC hoses with a rubbery goop.

https://originalair.com/restoration-mopar-heater-valves
 
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Oldbee is correct in principal only it is applied to the heater side. From an old article on Hemmings:

"Many of the more expensive models of car in the 1950s and early '60s used a thermostatic heater valve. These valves incorporated a thermostatic capillary tube that measured air temperature within the heater box and adjusted coolant flow according to the driver's desired settings on the dashboard. This same capillary sensor idea was used on thermostatic expansion valves on air conditioning systems for many years. Thermostatic valves can be the most difficult type of heater valve to find when a replacement is needed; however, several Hemmingsadvertisers do have them available. Other suppliers can perform restorations on these older valves."


It is basically a feedback system to try to modulate the coolant flow to maintain a constant heat temperature
 
Oldbee is correct in principal only it is applied to the heater side. From an old article on Hemmings:

"Many of the more expensive models of car in the 1950s and early '60s used a thermostatic heater valve. These valves incorporated a thermostatic capillary tube that measured air temperature within the heater box and adjusted coolant flow according to the driver's desired settings on the dashboard. This same capillary sensor idea was used on thermostatic expansion valves on air conditioning systems for many years. Thermostatic valves can be the most difficult type of heater valve to find when a replacement is needed; however, several Hemmingsadvertisers do have them available. Other suppliers can perform restorations on these older valves."


It is basically a feedback system to try to modulate the coolant flow to maintain a constant heat temperature

Thanks! It does sound kind of unnecessary from the description, especially in Florida where the use of the heater is minimal. Elimination may require some additional fiddling with the cooler/warmer lever on the dash control, but that sounds like the extent of the impact of it being inoperable.
 
Classic told me the they stopped doing this in '71

Might have been a bell and whistle that never really rang or tweeted! That makes it sound like Chrysler figured it was unnecessary and decided to save $5.00 a car.
 
Might have been a bell and whistle that never really rang or tweeted! That makes it sound like Chrysler figured it was unnecessary and decided to save $5.00 a car.

Logical reason there are norepops too.
 
My money says it really did not work that great and they had a newer more "modern" auto temperature design by the 70's.
 
If the wire is broke or pinch off, n not installed inside the heater box you would think that the valve will not work as the wire senses temp change,either in a/c mode or heat,so the valve would only work with what's in contact with the air temp where it is exposed.
 
If the wire is broke or pinch off, n not installed inside the heater box you would think that the valve will not work as the wire senses temp change,either in a/c mode or heat,so the valve would only work with what's in contact with the air temp where it is exposed.

I have been playing with the valve. I think the way it works is the cable sets the major position and the modulation via the tube is just a fine tune, it does not seem like it is able to move the valve very far. Not sure yet but that is what it appears to me. I plan on calling the this guy in the near future about rebuilding mine. I should be able to get more information then.

http://www.heatercontrolvalve.com
 
Yup, talked to Jim at Heater Control Valve. This was a feedback system that would try to regulate the heat a little. It was a gas valve and once the line is cut it is all over. He said the adjustment of the feedback was very limited and when he rebuilds them he installs a pin to lock this adjustment to a fixed place. The the cable is 100% in control of the valve and it can't move on your randomly because the gas value is moving around. He gets $109 to rebuild + shipping. Mine is going out tomorrow. He said he has some NOS too if you are doing a 100% correct restoration.
 
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