Odd Vacuum Problem

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Aug 2, 2013 | 11:02 AM

CaptKen

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Odd Vacuum Problem

02 F250 with 7.3. When I activate the 4WD, my light comes on, the A/C quits blowing out of the forward vents and goes into defrost and no 4WD. If I sit and wait a bit, the air again blows out the front vents and the 4WD engages. I figure I have a vacuum leak somewhere in the 4WD system. Is there a common place for this to happen or do I need to trace the whole system down? Also my manual hubs has never been turned and of course they won't. I know better than use a wrench so is there a easy way to free them up or just go ahead and disassemble and clean?

Aug 2, 2013 | 09:42 PM

redford

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From: Stephensville WI

Do you have a manual 4 wheel drive system (has a lever in the cab) or ESOF (has a switch in the cab)?

Aug 2, 2013 | 09:54 PM

CaptKen

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Switch on the dash.

Aug 3, 2013 | 08:02 AM

projectSHO89

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From: St Louis

You have vacuum leak in the ESOF system. Very, very common.

Check the PVH solenoid next to the battery and check the vacuum lines down to the hubs. One of them is leaking.