04 Tahoe - Air Conditioning Issue

PANDA

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This is one of those issues that I can leave the truck with the mechanic to fix and after having it for a few days he will tell me everything is fine and he had didn't see any issues. Intermittently the air conditioning will just start to blow hot. Seems to happen at random regardless of how long I would be using AC and what temperature it is outside. AC blows hard and cold all other times. I put 1500 miles on the truck and probably 24 hours of driving the past weekend and the issue happened 3 times. Truck is digital climate control so I almost think this is a sensor related issue.
 

RICH17

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Like it blows warm or the heat is on?
 

daturbosix

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my wifes trailblazer does that from time to time.
ive found if you shut the vehicle off and restart it, it will be fine.

im just waiting for it to completely fail before figuring it out.
 

willizm

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Yeah I've had the same thing in the escalade. It seems like if I don't run heat or AC for a long time and then turn it on, it does the opposite of what i'd want it to do. I turn on the AC and it blows hot. I shut down the SUV and start it again and it's fine and haven't had an issue since. I think this happened to me twice in the past 4 years of having the suv.
 

PANDA

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Might have to just take it to the dealer if this issue is as common as it sounds. Maybe they have a fix.
 

daturbosix

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its hard to diagnose something thats not broken though.
 

Bruce Jibboo

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not really, they will make you agree to per hour and let the tech drive around all day.
 

mweber

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Is the compressor still engaged when it happens? Had an 01 Sierra that did that, due to not enough air flow to the condenser when stopped or low speed. It would trip the high side pressure switch and disengage the compressor clutch. Replacing the fan clutch fixed the issue.
 

bikrboy128

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i've done countless blend doors on GMs for this exact issue. is the truck have dual zone climate control? next time it's blowing hot, check the passenger side vent.
 

CMNTMXR57

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My guess is blend doors too. A lot of the GM digital HVAC headunits with the dual zone control seem to have this issue. Doesn't matter if it's a GM truck or car.
 

ilikemtb999

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I recall this on the dual climate controls on the w bodies and was always the blend doors
 

bikrboy128

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the actuator is cheap, and if i recall the driver's side is the easy side to get at. you have to pull the upper part of the dash to get at the passenger side actuator.
so if it's the driver's side it might be worth it to replace as "diagnostics"
 

PANDA

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i've done countless blend doors on GMs for this exact issue. is the truck have dual zone climate control? next time it's blowing hot, check the passenger side vent.
Yup duel zone digital climate control. Pass side blows cold when it does this.
 

bikrboy128

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Yup duel zone digital climate control. Pass side blows cold when it does this.
yeah, it's the driver's side actuator then. you can get to the driver's side actuator without pulling the dash out.
on the passenger side near the trans tunnel hump there's a plastic guard bolted to the bottom of the dash (spans from the trans tunnel hump almost to the end of the dash). remove that, and the actuator is near the trans tunnel. you can watch it move while you turn the temp from hot to cold (with key on and HVAC on obviously)
 

PANDA

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Replaced the blend door actuator last night. Didn't really notice anything wrong with it but replaced it anyway. All is working on a quick 20 min drive so far!





 

b4black

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I had one of those little motor in a an Oldsmobile that I could see working though the glovebox. It would be fine for days, then just flake out and start opening & closing randomly. Replaced it, worked for a while and then did it again. Figured it wasn't the motor, but the signal to it.

I just gave up and manually forced open the door in the summer for AC only and then let it close in the winter for heat only.
 

PANDA

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signal might make sense also. It would change from AC (cold) to Heat without me touching the controls. But since the pass would stay cold I went ahead and replaced the actuator like Matt said. Hopefully it fixes it.

oh course my truck uses the most expensive actuator they sold. :(
 

CMNTMXR57

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Replaced the blend door actuator last night. Didn't really notice anything wrong with it but replaced it anyway. All is working on a quick 20 min drive so far!





That worm gear in there also likes to strip. That was the issue last summer on our Impala SS. Whenever you put it in recirc mode, or shut the car off, it would try to close it, and all you would hear was the gear grinding for a few seconds, stop, try again for a few seconds, and repeat this process 4 or 5 times. :D
 

PANDA

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Yeah restarting the car would fix the heat issue when AC is on. Gears look OK when I opened it up.
 

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