Vacuum Controlled Heater Core Valve

Well another great thread. Not that I am surprised! Sure missed everyone and their awesome progress. Looking forward to catching up on everyone's "onion peeling" This project has crossed my mind and I went out and ordered 2 three-way T-port valves and planned on doing all this manually under the hood, but now I am really reconsidering using a vacuum shut off. I am of the persuasion that I would like the core shut off on everything but heat as well. (I am tinkering on Ferdinand again; '85 Bronco XLT, Factory AC <but removed after the fire>)

I am reeeeeaaalllly disappointed in the current replacement cores. Cheap enough for sure but I think the heat sync is nearly 1/2" thinner!

Anyone have any good recommendations for sealing the airbox back up? Planning on just using black butyl unless someone can steer me in a better direction. (I really don't want to seal it up with silicone or permatex.

Thanks again guys for all the GREAT info!!

I would like to say after this summer, that I’m thinking of taking the valve out and hooking up the heater core as stock.

With the forest fires I use the Max A/C to keep as much of the bad air out that I can. It wasn’t real hot out one day, but hot enough for A/C, and I don’t want the vents or to open the windows.

There is no controlling the temperature. It was just cold, without the heater core being warm all I could do was turn down the fan.

Thanks for the feedback Dane. I think I am going forward with the manual valves. That way I have 100% control of when the heater core is in use. Plus I like the idea of when it is off, I am recirculating back to the block. I may feel differently once I get my factory air rebuilt but I am not sure when that will be. But in case I run another summer with out it, keeping that hot box from bleeding heat into the cab in July has got to be a plus! I do run my vent a lot, but I can understand why you don't and I likely would do the same in your shoes. I really like the look of the install on your Bronco. Mine is a bit older but I plan on fabbing up a mount for the 3 way valves almost in the same location that you have your bypass valve.

I'll upload the project for the benefit of another option. Though, most folks would likely take a hard pass on the idea. We shall see how it goes. Valves supposed to be in come in Friday.