Temperature Control
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Temperature Control
I have a 99 F-150, 2WD, 5.4L Super Cab. The temperature control for my ac/heat is going crazy. When I have it on heat, it will blow cold air most of the time. It will warm up occasionally, but then go cool again.
The opposite when I use my AC. It will blow cold air for awhile, but it seems like if I hit a bump, or stop at an intersection, the air will go hot and stay that way.
There really is no pattern that I can figure out, it just gets hot or cold when it wants to.
When I rotate the temperature **** it feels normal, except occasionally it will feel like it skips about a third of a turn, I notice this because all friction on the **** goes away and then comes back. I can rotate the **** back in the direction it came from and it will feel fine, but it will have no affect on the temperature coming out of all the vents.
It does it from all vents, defrost, floor, panel, etc..
Any suggestions would be greatly appreciated.
The opposite when I use my AC. It will blow cold air for awhile, but it seems like if I hit a bump, or stop at an intersection, the air will go hot and stay that way.
There really is no pattern that I can figure out, it just gets hot or cold when it wants to.
When I rotate the temperature **** it feels normal, except occasionally it will feel like it skips about a third of a turn, I notice this because all friction on the **** goes away and then comes back. I can rotate the **** back in the direction it came from and it will feel fine, but it will have no affect on the temperature coming out of all the vents.
It does it from all vents, defrost, floor, panel, etc..
Any suggestions would be greatly appreciated.
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Joined: Oct 2005
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From: Louisville, Kentucky
Welcome to FTE Bassgod. 
Three things come to mind with what you described.
Three things come to mind with what you described.
- As LxMan said, broken blend door.
- Could also be a broken temp control ****. Try switching the temp **** for one of the other control *****. These ***** tend to crack adn therefore won't grip the shaft properly to turn it.
- Finally, there is a vacuum line that comes through the firewall to supply vacuum to the controls. If this line is cracked, leaking air, then the sysptoms that you are having could occur as well.
Hotshot
Joined: Jul 2005
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vacuum controls more of the direction the air goes--- defrost or floor. the two most common problems are as KR said, the **** could be stripped and spinning on the shaft, or the blend door arm is broken (or its motor stuck).
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Thanks for giving me a good starting point guys. I will dig into it this weekend hopefully. Do I have to drop my entire dash if it is the blend door, or can the duct work be dropped without that mess?
Hotshot
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the normal procedure is to take out the dash. Some of the Explorer guys have found a way to remove the glove box door and cut a hole into the duct with a skill saw and pull the door out. I have not heard of a short cut for the F150.
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also could be the motor/actuator that operates the blender door, that's what mine wasa and i had same symptoms. I would make sure to check the **** first hopefully that's what it is and you won't have any problems.
good luck,
TJ
good luck,
TJ
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Junior User
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Sounds like the temp control **** is broken where it slides onto the rheostat shaft. I had a similar problem.
Just pop the **** off and swap it with the fan control ****. If this fixes it then you're good to go. If not, then you can go deeper.
Good luck
Just pop the **** off and swap it with the fan control ****. If this fixes it then you're good to go. If not, then you can go deeper.
Good luck
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