Ford Explorer 1992 heater control valve install

living in Florida means you want MAX AC from your car or truck. The 1st gen explorers did not have a means to turn off the hot water to the heater core (installed inside the truck under the dash) until 1994. I presume the use of 134a vs R-12 may have prompted ford to look at ways of maximizing the cooling (presuming R-12 was better than the 134a) since I think the 134a started in 1994. Anyway rarely needing heat, I opted to add this cutoff valve, tied into the vacuum circuit of the max AC servo, thereby cutting off the heat completely so no radiant heat or if the blend door does not seal perfectly no heat from air leakage thru the radiator.
I went back and got that heat hose fully seated after reaming the hose a bit on the one that was not fully seated. I also stuffed the insulation and got the metal foil tape to fix the missing insulation over the evaporator box.

[@jockodog2009]

The vacuum line is the dilemma for most people, especially if one wants to install that valve on a car that didn't come with it. In those years,, the MaxAC mode only operates the recirculate door below and to the right of the glove box. That vacuum line must be tapped with a tee-fitting, then an additional vacuum line is run through firewall to the new valve. BTW, the valve looks upside down. Actuator should be on the bottom. There should be an arrow on the valve indicating direction of flow, inlet hose side.

[@PolishAlexx]

What would happen if the vacuum source was the intake? Is it so sensitive that just idle/low load would trip it? I'm looking to use this for a performance build whereby I can redirect more coolant to the radiator once the vehicle is under heavy load.

[@jockodog2009]

@@PolishAlexx The intake is the source for vacuum. Distribution is then to the vacuum reservoir to maintain vacuum (for recirc door and heater diversion valve mode) for high load/high RPM situations when intake vacuum drops. I don't know about your particular after-market performance upgrade.

[@Farmradio]

Funny, just tried my heat & blower today. Already getting chilly at night here in New England. Neighbor a few houses up, sold everything & left for Ft. Meyers. No more cold & winters for him he said. Gone as of Tuesday.

[@davewm9589]

I need to move to New England then, sick and tired of the heat. I was testing it last night 8pm out side air temp 90 degrees, and humid as heck.

[@Farmradio]

Dave WM That is a bit unbearable. I'd love to be what they call a snowbird. Leave here in December, return in April. Gladly trade those months.

[@davewm9589]

Farmradio yep that's the way to live in Florida. The freaking humidity is crazy, you practically need gills to walk outside.

[@audubon5425]

I believe you have the flow right - the water pump should suck from the heater core. The Fox and Panther cars were set up like that too - constant flow through the core.

[@zarthusmaximus7841]

Great video thanks hairy beast man! XD Very helpful!

[@tomthumb1894]

it's on backwards

[@franciscoadolfo5805]

Why?

[@kn4cc755]

I must have missed where the vacuum line is connected to. Anybody see that?

[@davewm9589]

My 92 did not have a vac hose for this purpose, so I had to add one. I connected a T connector at the bottom of the servo inside the cab that is used to recirc the air. This servo only activates when the control is set to "max ac" the servo is on the passenger side next to the glove box. After installing a T connector you route a vac hose thru the fire wall where there is a large hole for the wire harness.

[@JamieTransNyc]

Usually water comes OUT of the water pump and to the heater and the radiator, If so, you have plumbed the valve wrong.

[@iDrive512]

I see that you added the vacuum line to your '92. I am wanting to accomplish something similar. Where did you obtain the OEM looking vacuum line that runs from the new T connector to the new coolant bypass valve? I know any vacuum line is good to go, but just curious where you got your white one with the 90 degree end?

[@davewm9589]

been a while but I think from a local junk yard. They are great for picking up little parts that are hard to describe.

[@jordanposvar3616]

Where does the thin grey line on top of the valve go to? Im trying to replace mine

[@davewm9589]

there is a vacuum line that connects inside the passenger compartment to the servo that activates the vent/recirc door, its on the side of the car covered by the glove box.

[@jackwild1111]

Put some vasoline on it... It'll slide right on !

[@aameiel]

Where does the vacuum line go to ?? Mine is broke can’t figure out where it goes

[@davewm9589]

the vacuum line goes to the bottom of the actuator that opens and closes the recirc/vent door. by glove box, inside the car. The 1992 did NOT have this setup for the valve I added. I used a "T" connector to tap that vacuum source and fed a line thru the firewall at a grommet plug. The recirc/vent vacuum is activated when the controls are set to "max" ac, so only then does the valve shut off all hot water to the heater core.

[@aameiel]

Dave WM ah ok I have a 1997 Explorer XLT 5.0L and noticed while I was replacing the egr that this vacuum coming off the heater valve was broke and just dangling. I’ll look into it tomorrow during the daytime thank you for the reply!!!!!

[@davewm9589]

dig around the firewall look for a larger wire harness, often the vacuum lines will be incorporated into the wire harness to get thru the firewall. The line itself is pretty hard to spot since its thin and often made from a hard looking plastic that can be overlooked as a wire. Find the big wire harness on that side of the engine bay and then start looking for that hard plastic tube. Warning they can be brittle, may be broken short of the valve, good luck!

[@aameiel]

Dave WM found it thank you so much !!!

[@alimvinca2998]

How’d you find the valve, I haven’t been able to find one. Can you give me a part number or a link?

[@davewm9589]

Junk yard find.

[@davidgruen7423]

F87Z-18495-AA

[@jackwild1111]

Handy as a fart in a spacesuit !