AC coolant diverter valve - vacuum line? | Ford Explorer Forums - Serious Explorations

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AC coolant diverter valve - vacuum line?


Active Member
May 21, 2018
Reaction score
City, State
San Antonio, TX
Year, Model & Trim Level
'91 Explorer Sport 2D
Hey yall

Which of these two lines gets connected to the vacuum actuator port on the AC coolant diverter valve? Theres one coming up with the wiring harness, and another coming off of the black canister. Where does the other vacuum line go?

Photos attached.



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Most first gens didn't have a coolant diverter valve from the factory. Many people have added them, basically pulling them from 2nd gen explorers. When that is done a vacuum line is run from the max a/c recirc door valve under the dash (t'd off it) through the firewall to the diverter valve. That way when max a/c is on the coolant isn't allowed into the heater core.

From the limited view in the pictures and from what I remember... The vacuum line coming off the canister goes into the cab for recirc door etc. I believe that's the only vacuum connected to the canister. Everything else runs on engine vacuum instead of a constant vacuum.

The one line I can't remember though is the one that goes to the pre-heated intake valve. It's the one on the intake hose between the front of the vehicle and the air filter. For some reason I'm thinking that one may run off constant vacuum.


So maybe the 2 pictured vacuum lines need to be connected (The one coming off the canister to the one coming out of the wiring harness? And as for the diverter hose, maybe it's not even there yet (NOT one of the 2 pictured)? I bought some 1/8" hose and connectors/tees, so I can make it happen. Any pics would really help save me a trip to the junkyard.


The diverter valve in your picture is mechanical, which I've never seen on an explorer. You basically change the direction of the flow of coolant by opening/closing valves. That's more or less the kind you open in fall and close in spring.

I didn't drive the X to work (I don't take it into town much at 14 mpg) so I can't post a pic but right now my gut is telling me those 2 lines you see should just be connected. I have also done the 1/8" hose over broken plastic lines before so that should be just fine.


Sorry, I should have clarified. I have the diverter valve ready to install, the PO put on these mechanical valves. First time I went to look at them, one was fully closed. With it setup like that, there wasn't coolant flowing through that part of the "circuit"

Anyways, I actually found 2 different types of valves on 1st gen explorers. One type has 4 hose barbs, obviously 2 to the motor, 2 through the firewall. The other type only opens the valve on the heater supply hose, with a straight connector on the other hose. I suppose with it setup like this, the coolant flow would be similar to the above mentioned "mechanical valve scenario"