4x4 A/C issue
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New User
Joined: Feb 2016
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From: Lake Elsinore, CA.
4x4 A/C issue
I have a 2002 Ex with the 7.3. Every time I put it into 4x4, the A/C automatically switches to the windshield defrost vents. After a couple minutes it switches back the the A/C vents. I'm assuming that isn't normal. Anyone else have that issue?
Laughing Gas
Joined: Oct 2013
Posts: 861
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From: AZ
The A/C uses vacuum to operate the dampers which control where the air flows in the dash. The 4x4 system uses vacuum to actuate the hubs. You have a vacuum leak somewhere causing the 4x4 system to rob the A/C system of vacuum for controls.
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
No, that would be a different issue with the AC system, probably a low charge. Vacuum ONLY affects the outlet door selection and the recirculate door and heater control valve (if equipped) if in MAX.
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
If the vacuum leak is ONLY when the 4x4 is engaged, then it's a leak problem downstream from the PVH solenoid 99% of the time. That means it's almost always either the vacuum lines to the hubs or a leaking hub.
Faulty PVH solenoids usually leak all of the time, they don't care whether or not the 4x4 is engaged or not.
Faulty PVH solenoids usually leak all of the time, they don't care whether or not the 4x4 is engaged or not.
Senior User
Joined: Jun 2015
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From: Bridgeport, WV
If the vacuum leak is ONLY when the 4x4 is engaged, then it's a leak problem downstream from the PVH solenoid 99% of the time. That means it's almost always either the vacuum lines to the hubs or a leaking hub.
Faulty PVH solenoids usually leak all of the time, they don't care whether or not the 4x4 is engaged or not.
Faulty PVH solenoids usually leak all of the time, they don't care whether or not the 4x4 is engaged or not.
I posted in another thread with same issues, got no response......With new Dorman hubs, how would one test for a leaking hub?
Swmpbgy1
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More Turbo
Joined: Dec 2012
Posts: 719
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From: WisCONsin
Me too mine changes the blower doors at 2k rpm: acceleration, and high hwy speeds
Does anyone care to post a pic of this thing?
I found one and see there is a red and black vac line, but there are vac lines all over the place and I'm solo testing and haven't picked up a vac pump but will soon, maybe this weekend
Does anyone care to post a pic of this thing?
I found one and see there is a red and black vac line, but there are vac lines all over the place and I'm solo testing and haven't picked up a vac pump but will soon, maybe this weekend
Elder User
Joined: Oct 2015
Posts: 949
Likes: 1
From: SoCal
What about 2nd row not blowing but front and 3rd row work fine? After this last trip driving in 113° weather kids in 2nd row got warm. We recently had some solenoid replaced but didn't help. Will look up in paperwork what exactly was done if needed.
Senior User
Joined: Jun 2015
Posts: 165
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From: Bridgeport, WV
This is the drivers fender well just to the right of the shock. Look under the spash flap.
This is the drivers front axle looking down and to the left.
It will be the same on the passengers side.
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