Yeah I love that O'reillys can get Motorcraft parts, and also they seem to have stuff in stock more often. I was at an Autozone further in town when I was looking for vacuum line initially (mainly because the O'reillys where I live was closed at that particular time of the night since it's a small town) and they didn't have any vacuum hose or tees in stock... so I had to wait until the next morning to start this project.

 

Awesome writeup will be doing this mod to my f150's soon.

 

Thanks! I'm glad the writeup will be of help!

It's starting to get hotter here again so I'll be to feel the effects of this mod more when I use my AC! Anything that cools the AC down here in AZ helps!

 

I've never seen a bronco or f150 that didn't already have this part? All the ones I've seen always had a vac operated valve to keep hot coolant from entering core when a/c is on.

 

Hmm that's strange. I've never seen a bronco/F-150 of this era or earlier with the vacuum operated valve to keep hot water from entering the heater core. We had an '88 F-150 a while back with the 5.8, and it didn't have this valve. My bronco, nor the other ones I have seen in person (only about 2), have had this either.

I do not believe it was an option that came from the factory, but I could be wrong. Maybe, all the broncos you have seen have had this installed by a previous owner?

Is the valve that you've seen connected between the two heater hoses like in the pictures posted? Or is it in a different location? Maybe you're mistaking the valve for something else? (I'm not at all trying to say you don't know what you are talking about, I'm just pretty sure that this valve wasn't stock until the 97+ explorers/expeditions came out so I would be shocked if this was an option from the factory.)

 

I know it was factory on 78/79 Broncos with air. Its in the manual and my 78 has it. As far as being stock on anything else I couldn't tell you but I've never seen a Ford that didn't have it. Strange!

 

None of the full size bronco's ever had the bypass valve. They didnt show up till the Explorer/Expedition came out. Dunno about your 78/79 though. But I look at zillions of these all the time in the junkyards and have never found a full size F-series 88-96 with one ever.

 

78/79 fullsize Broncos have them and so do the 73-79 F-series trucks. Its just a different version. It blocks the main flow coming from out of the block so hot coolant isn't pumped directly to heater core.

Never seen a 80-90 Bronco or F150 without one either. I guess tons of people did the mod years ago.

 

It was common for the cars and trucks of the 1970's with A/C to have a vacuum-operated water SHUTOFF valve in series with the heater core inlet hose. The valve would close when the A/C controls were set to "Max".

None of the full-sized 302 cars we had in the 80's had them. Although people who had ATC would often think they did, mistaking the ATC temperature switch in the inlet hose for a shutoff valve.

I've never seen an actual factory-installed heater BYPASS valve, myself, since I've never had an Explorer or Expedition of any year.

 

I'm not saying its factory on the newer vehicles but obviously people started doing mods like this many many years ago. Like I said before I've never seen one that didn't have the shutoff valve. My 92 F150 even has one and I didn't put it on.