2003 Ford F-250 Vacuum line

PACAMPER

MEMBER
2003 FORD F-250
V8
4WD
AUTOMATIC
85,000 MILES

Hi.I have a 2003 F-250 Diesel. Recently my automatic front hugs quit working. They work fine when I lock them in manually but they don't engage automatically. Also my heater/AC selector switch will not change positions, it only comes from the defroster vents. It will not change to panel or floor. Does anyone know if these two items are controled by engine vacuum or not? Any advice is greatly appreciated. MIke

Friday, March 14th, 2008 AT 4:11 PM

3 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Yep! There will be a reserve tank for the heat a/c register switching, is the vac pump on the truck working? Put a gauge on it and see if it's at 18-22Hg.

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Friday, March 14th, 2008 AT 4:21 PM

PACAMPER

MEMBER
2 POSTS

Thanks merlin. The old pump was not working so I replaced it. My auto hubs and my panel vents now work but I must have a leak in a line or the resevior tank. If I shut the truck off with the panel vents selected and wait for a while, when I start back up the defroster vents are active until the pump picks back up and then it switches back to the panel vents. I confirmed this with a friends truck, his remains on the panel vents after restarting the vehicle hours later. Does anyone know of a easy way to find a vacuum line leak?

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Tuesday, March 25th, 2008 AT 6:54 PM

MERLIN2021

MECHANIC
17,250 POSTS

Get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! With a diesel it's harder, you might need a smoke machine.

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Thursday, March 27th, 2008 AT 2:54 AM