I added a manual heater shut off valve the prevents hot coolant from entering the heater core on my Mustang, and have been thinking about doing the same thing in the F150. Has anyone done this on their truck? If so what style did you use and where did you install it? The way I did it in the Mustang will not work on the truck.

 

I have. Used one from a ranger with a vacuums control. Shuts off coolant flow on Max a/c

 

It's just a rubber hose so any valve that you could press in and clamp to the hose should work but wouldn't it be better to put a bypass in rather than just a shut off valve?

 

I had one on my SuperDuty and it helped a lot, so I put one on my F150. It didn't make any difference.

 

That sounds like a good idea, but I want it shut off unless the heater is on or manually shut off.

 

This was my first thought.

 

I don't see how it couldn't make a difference. It still radiates heat when not being used.

 

What can I tell ya? That was my experience.

 

Seems kinda odd. Did the vent blow cooler air at least, when not using AC?

 

I could be wrong but the heater core shut off is just a Band-Aid fix for an inproperly adjusted or leaking blend door in my experience. If the hot/cold blend door is working properly the shut off will make very little difference, no air should go though the heater core on the cold setting and the only small difference will be slightly less heat in the firewall area but this is negligible as it's already inches away from the engine.

 

No, doesn't make any difference. The SD has a kind of shelf under the hood over the firewall that traps a lot of heat, and a hot heater core just adds to this. Perhaps the air box on the SD is not insulated well, or cordoned off well enough from the flow of cold air. All I know is heater core shutoff valves are very common on SDs, this is a well-known problem, but not so much on our trucks.

 

The heater core is inside the cab. Even when the HVAC is completely off, it will radiate heat.

 

The heater core is in the AC/heater airbox in the engine compartment. It might radiate some heat through that but it's also inches away from the Engine. Van's and SUV's with rear climate control do have heater cores inside the cab.

 

The heater core is behind the glovebox inside the cab and the a/c evaporator is on the outside of the firewall closer to the engine, but they do share the same plenum.

We can solve this real quick... take an IR thermometer and scan the outside of the heater plenum behind the glovebox and take note of the surface temperature with and without coolant flow going to the heater core. I bet it does not make much difference.

Agreed. If your blend door works right then you shouldn't have any air going thru the heater core anyway.

 

The box is in the engine bay, but the core is in the cab. The ports from it go through the firewall.