Heater Control Valve
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Junior User
Joined: Aug 2003
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From: Hereford
Heater Control Valve
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 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??
Fleet Mechanic
Joined: Jan 2012
Posts: 1,841
Likes: 6
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.
Fleet Mechanic
Joined: Feb 2011
Posts: 1,812
Likes: 88
From: Thousand Oaks, CA
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.
Fleet Mechanic
Joined: Jan 2012
Posts: 1,841
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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
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Junior User
Joined: Aug 2003
Posts: 64
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From: Hereford
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!!
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New User
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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
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Fleet Mechanic
Joined: Feb 2011
Posts: 1,812
Likes: 88
From: Thousand Oaks, CA
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.
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.
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