Gentlemen,

I'm thinking of this for my '79 F250, but am posting in general 'cause it could pertain to most any vehicle.

The "off" position of my heater controls really do nothing but block the flow of air into the cab. But coolant is still flowing wildly through the heater core all the time. So, (a) there's always at least some hot air filters into the cab - deadly on hot August days - and (b) it must get really really hot inside that heater box.

Sure, I could short one hose to the other for the summer, but too much trouble. I'm lazy.

So, I was thinking about installing a ****-valve into the hose that supplies coolant That way the whole heater circuit isn't under pressure all summer, as it would if I put the valve on the return hose.

Does nayone see any pitfalls or good reasons not to do this that I haven't thought of?

Thanks.

 

Hmm, my 79 F150 (w/ a/c) has a vacuum operated valve inline on one of the water lines to the core. And it does shut off flow when its not on heat, at least not when its on vent or a/c. Maybe your truck used to have one too but it was bypassed? Might be worth looking into whether you can add one back in for cheap. I recently had it replaced when my a/c was fixed because it was leaking slightly, and it wasnt bad at all.

If you truck wasnt equipped with one originally (maybe for non a/c equipped vehicles?), if the vacuum worked right maybe you could tap off a line under the dash that had vacuum when heat was selected or something like that.

 

Ford started putting valves in just the a/c trucks in 73, before that all of them had it. It's a great idea, but if your weather is anything like what we have here, you'll be popping the hood twice a day to switch the valve- once in the morning to get the dew off the windshield, and again in the afternoon to turn the heat off. There's about a 30*F temp difference here between night and day.

 

go to the parts store tell them you need factory air part # 84706. thats a manual shut off valve for a 5/8 heater hose. Got one for my 78 f250 just have'nt put it on yet.

 

Moved to proper forum.

 

Excellent news! We'll be gettin' some heat relief real soon....

 

I put one on my 99 v10. It took 3ft of 3/4 heater hose and a manual shutoff valve. Cost me about $25 and my temp is running about 5 degrees cooler. Made a big difference, when I wake up at 6 in the morning it is already 78-80 degrees outside here.

 

Take a look at my gallery. I put a ball valve in the line and the vent temps dropped nicely.

 

My brother put a cable-operated cutoff valve in the heater core hose in my '74 highboy.

I put a stainless ball valve in line to the heater core in my '01 Superduty because it didn't come with a heater core shutoff.

Both trucks are/were much cooler with the heater core shutoff...

 

Our Mack trucks at work have both set ups. They have the cable (Which usually rusts and locks up) and they also have a spigot type valve which works great. It definately keeps it cooler in the cab.

 

What years did Ford provide such a cut-off valve? I have an '87 F-150, factory air, and am having fits trying to get the air cold in the summer. I bypassed the heater core and now have air 35-40 degrees cooler than ambient air (usually around 95 here in central Oklahoma). Maybe mine had one, but no more? Where does it go? What vacuum lines control it?

 

I know my '01 Superduty didn't have one, but the Crew-cab DID. Bigger interior, more call for cold air. It seems to be hit or miss all the way back through time whether or not it came with a cut-off.

The cutoff is usually plumbed into the MAX A/C vacuum line. No idea which one that is for you