Join Date: Aug 2010
Location: Sassamansville, Pa
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That is just a vacuum operated valve that some trucks have and some don't (depends on model), it just closes off the coolant flow to allow cooler A/C in the cab.
If you removed the gray line, you should block off the vacuum so you don't have a vacuum leak. Ford was kind enough to put a nipple on the HVAC box for you to block off the gray line. If you look at where you refill you motor oil, behind the oil fill an to the side, on the HVAC box you will see this nipple sticking out. Just plug in the gray line their untill you replace the valve.
Edit: below my finger you will see where it goes if not using the valve.
2004 F350 CC DRW King Ranch
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