Heater/ac issue
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Senior User
Joined: Dec 2011
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From: Needville (Houston) Texas
Heater/ac issue
I am having a bit of trouble with my heater/ac mode switch I believe. No matter what position i put the switch on it only blows through the defroster vents. The only other position that works is off. When it is on off then it doesn't blow out of any vents. Does this sound like the mode switch itself or an actuator or something like that inside the system? How tough is it to remove the dash to get to this switch if it is just the switch?
Elder User
Joined: Mar 2008
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From: Ontario, CA
I'm guessing (MY BAD) you have 4WD; it is the Electronic Shift On the Fly hubs. They are vacuum operated. when they start leaking, heater/AC defaults to defrost. If you don't have 4WD, time to look at another vacuum line I guess...
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Senior User
Joined: Dec 2011
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From: Needville (Houston) Texas
ok. No, mine is a 2wd. When this happened with my jeep it was just the switch but I will start looking at a vacuum leak i guess. It's not that big of a deal except my feet are cold!
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Don's got you on the right (vacuum leak) track.
The Federally-mandated "default" failure mode is Defrost. That's all the Feds consider to be absolutely necessary.
Even though you're freezing, you legally have to be able to see out the windows!
Pop
The Federally-mandated "default" failure mode is Defrost. That's all the Feds consider to be absolutely necessary.
Even though you're freezing, you legally have to be able to see out the windows!
Pop
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Senior User
Joined: Dec 2011
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From: Needville (Houston) Texas
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Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
First, make sure your vacuum pump runs. That's where you get your vacuum, as diesels don't have any intake manifold vacuum. The truck still needs vacuum to run the HVAC controls and baffle servos..
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Joined: Apr 2009
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When I first bought my truck it had this issue found out that the vaccum pump was n/g. replaced it and havent had any issues. If you need one 1aauto has one with lifetime warranty. I had one fail, called them up and they sent me a new one no questions asked.
hope this helps,
-AJ
hope this helps,
-AJ
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Senior User
Joined: Dec 2011
Posts: 221
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From: Needville (Houston) Texas
It was a fuse to te vacuum pump. The different part is that you couldn't tell the fuse was broken from looking at it. An ohm meter on te fuse confirmed the circuit was broken and a new fuse got it going.
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