Had the truck at the dealer to look at the heater. I have heat coming from the floor when the controls are off. The blend door is working because I can get hot or cold air when AC is on, He said there is not a heater control valve and that it is normal for heat at feet when turned off. I should just open the windows and turn control to vent and aim them at the windows.
I can't believe this. I can find a heater control valve on Rock Auto for my truck but I can't find it on my truck.
Who is correct and where is the valve??

 

I removed the panel behind the glove box and confirmed the 2 doors are intact and moving. I also confirmed the heater core is always hot.

 

If you have a heater control valve it will be on to top hose going though the firewall to the heater core on the passenger side. If your truck is not a crew cab it won't have a valve from the factory and from what I've seen there are even crew cabs that don't have them. None of my fords have ever had hot air blowing from the floor with hvac controls off. I have the part number for the valve that came in the super duty if you want it just got to go look.

 

Sorry it's a 1999 F250 Super Duty 6.8 V10 Super Cab 4 Wheel Drive.
There is not a valve there. It would be easy to put one in, but where would I get the vacuum from??

 

It would be surprising if it did not have one from the factory. My '70 Mustang has one.
The valve's purpose is to shut off hot water going thru the heat exchanger which is usually right next to the AC evaporator.
There should be a 1/8" plastic tube coming out of the firewall that would connect to the valve.
If the line is there it should be capped off if not in use.
To add a valve that is totally missing the vacuum would come from the heater control panel in the dash or tee off a vacuum line controlling a vent flapper when heat is selected.
If the control panel does not have vacuum (all electric) there is a small vacuum switch than can be mounted next to a flapper arm to control the vacuum signal.
The entire heat/AC should default to windshield defrost if there is a failure in the controls.

 

You can tee into the vacuum line under the dash if you want it to work like it does stock closes on max a/c only I think it's the white line but don't hold me to it I had the info somewhere but can't seem to find it right now. You can use a few different bad lines under the dash to get it to close in different hvac positions but like I said I can't find my info so I can't tell you what does what at the moment

 

I want it to close when controls are off. Maybe work with temperature blend door, it stays closed. I will look into it. If you find the info I would like to see it!!

 

I have an 03 regular cab, when I installed my heater control valve there was a vac line already in the engine bay and plugged into a nipple on the heater box. I just removed it from the heater box and plugged it into the heater valve and it works as it should. As a side effect, with the AC on max in 108* weather I will start loosing the feeling in my fingers because my cab gets so cold.

 

Great I will look. Was it on top or the side or front?? Color??

 

It's the grey colored vac line I circled in the picture.

 

Now that is good information!!!! I don't have one or those. Where is it coming from??

 

I think the gray vacuum line goes thru the firewall to the heater control panel in the dash.
It snakes around and goes down between the blower housing and the right fender out of sight.
There's a little stud on the front of the evaporator/heating housing.
That's probably where the line gets plugged in/capped off when the bypass valve is not installed.

 

I think that is the white one, seen on the left of the pic. The gray seems to go up and to the right.

 

The white one is for something else.
The gray one goes up and slightly to the right in the pic, but loops around to the left by the person's left forearm.

 

OK, I see it. There is only the white one on my truck. I'll have to look in the cab.