Heater Control Vacuum Line - Grey One | Ford Explorer Forums - Serious Explorations

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Heater Control Vacuum Line - Grey One


June 21, 2023
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City, State
Year, Model & Trim Level
1998 Explorer XLT
1998 Explorer 4.0 SOHC and the thin grey vacuum line from the heater control valve broke and I have no heat. Before the actual break, i did not have heat, so I checked the control valve with vacuum pump and it works fine. Then I thought to trace the line back and do the pump again to see exactly where the issue was. I thought the line went to the vacuum ball (Right front fender) and it does not, but I think it goes to the fire wall under the dash. Here are some pics of what I'm talking about.

The broken grey line

Then it goes under the blower motor or AC, or whatever it is and disappears

Then under the glovebox at the fire wall this is what I see. Does the grey vacuum line connect to the lines right at the firewall (on the other side maybe), or??


Trying to find this info is like looking for the Holy Grail...Any help would be appreciated...Ed

Best I can tell, yes, except my diagram shows a white vac line instead of gray, and I'm wondering if your gray line used to be white but is just dirty or otherwise heat degraded.

The diagram shows a white line comes from the console control module, splits with a Tee to go to the outside air recirculation door motor, and to the coolant control valve through the firewall. To more directly answer the question, yes the vacuum line to the coolant control valve connects to or is one of the lines at the firewall

I'm not good at interpreting close-quarters pictures, but it seems like your last picture, may be showing that Tee and where it goes through, then that 2nd, black line is the one going to the vac tank.


This thread has pictures


This thread has pictures

Thanks...Could have sworn I looked at this one, but nonetheless...super!! I'll get some vacuum line and see what happens..