f250 4x4 switch
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f250 4x4 switch
I have a 2000 F250 with about 170,000 miles. I have an issue when I turn the selector switch on the dash to engage the 4 wheel drive, the air conditioner will quit blowing air through the dash and will start blowing the air out as if it was on defrost. Any thoughts are welcome.
Elder User
Joined: Oct 2014
Posts: 607
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From: CT
Welcome to the Forum. I'm surprised no-body else offered an answer yet...
Your front 4x4 hubs have a vacuum leak. When you try to engage 4x4, the solenoid opens to pull in the hub and you're losing vacuum. The HVAC system selector door also uses vacuum to switch from floor heat to vent to defrost. For safety reasons, if you don't have vacuum, the HVAC defaults to defroster. I am betting that if your defroster switches in, then you probably don't have enough vacuum to actually engage the front hubs, you're only engaging the transfer case but not actually driving the front wheel (, unless your Hubs are LOCKED and not in the AUTO setting.)
Check the vacuum hoses that run to the hubs they're most likely the culprit - after 18+ years I'm betting that they're very brittle and full of leaks.
Some folks will just plug the hub vacuum lines, and then manual lock their hubs.
Good Luck,
RWNJ
Your front 4x4 hubs have a vacuum leak. When you try to engage 4x4, the solenoid opens to pull in the hub and you're losing vacuum. The HVAC system selector door also uses vacuum to switch from floor heat to vent to defrost. For safety reasons, if you don't have vacuum, the HVAC defaults to defroster. I am betting that if your defroster switches in, then you probably don't have enough vacuum to actually engage the front hubs, you're only engaging the transfer case but not actually driving the front wheel (, unless your Hubs are LOCKED and not in the AUTO setting.)
Check the vacuum hoses that run to the hubs they're most likely the culprit - after 18+ years I'm betting that they're very brittle and full of leaks.
Some folks will just plug the hub vacuum lines, and then manual lock their hubs.
Good Luck,
RWNJ
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