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Hey guys, I posted this earlier on the general topics forum before realizing there was a more specific forum for troubleshooting. I live in Phoenix and tend to run my A/C for quite a few months of the year. For at least a few months now my A/C seems to have developed a mind of it's own, it randomly decides to switch from blowing out of the forward facing vents to blowing from the defrost vents, and when it blows from the defrost vents it blows ice cold out of one, hot out of the other. Sometimes it works totally normal for a week, with full control of all functions, then, out of nowhere it just switches to defrost vents without me touching anything, then, randomly back to normal on occasion. I should add that whenever I get in the car I hear a small motor whine, which I am guessing is one or both of the air directing units moving. Since it continues to switch back and forth, I'm thinking it is likely the control unit rather than the parts that it commands but would like to be more certain before juggling parts. Any helpful tips would be greatly appreciated.
 

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If you are not running it in auto mode and don't have different temps selected driver and pass I would say it is a glitch in the control unit of some sort....
 

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If you are not running it in auto mode and don't have different temps selected driver and pass I would say it is a glitch in the control unit of some sort....
Thanks for the response. I did just pick up a replacement (although from a salvage yard) and things remain the same. Of course it's possible that the used replacement is also bad but with no change whatsoever (better, or worse) I'm starting to suspect it may be either the blend door actuator(s) or trouble with the blend doors themselves. I have the glovebox out and plan on removing the one for the passenger side tomorrow to test it. Hopefully that will be the problem, Aftermarket replacement is less than $50.
 

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If it just happens randomly I would guess it is some type of control problem seems like a stretch that it would actually be the blend doors...is there another thing that controls the AC not sure may want to go talk to the parts guy at the dealership and see a schematic or if you can find one online so you know where and what controls what....best of luck! What year is the demon any warranty left? Try removing the battery for a bit may reset something worth a shot lol
 

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Don't forget that the actuators are stepper motors and the shut and open positions need to be programmed in. There are a few threads on this topic. There 4 actuators on both side of the air con unit.
 

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thanks to all who have replied to my sporadic A/C venting concern. I have temporarily solved the problem by pulling the glove box and manually positioning the vents directly associated with the passenger side blend door actuator, while unplugging it too. It seems that the actuators go through an auto programmed synchronization sequence whenever the car is started, I think the gears in the one on the passenger side may have started to strip, so that one would randomly stop in different positions during the calibration process, creating some frequent climate control chaos. I will add that I did change out the control panel earlier during my attempt to fix things, but found that I had the same problem following that effort. Still haven't installed the new actuator as I live in Phoenix, and am currently just thrilled to have my a/c working for the summer, but have it ready at hand and will probably just do it in the fall.
 
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