How to fix Hot Air when A/C is on. Install new air mix/blend door actuator

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SmokChsr

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I have been having a problem of Hot Air blowing out of the passenger front vents when the A/C is turned on.

One side note to this.. Until you replace or repair the actuator, you can usually turn off and on the motor and it will go back to cold when it does the reset. It also helps to keep the temp set to the lowest setting so the computer doesn't try to reposition the blend door and it stays on full cold.

Mine is currently in need of attention, but being lazy, I just work around it for now. So I'm quite experienced at restarting when needed.

The cause of the problem is the position sensor in the actuator (a variable resistor) is dirty and not making good contact. While I havn't done it myself (yet) I've seen it said that you can open and clean that resistor and it'll work fine again.
 

SmokChsr

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I made a new thread on it, but the new actuator didn't do it for me. Same exact symptoms as the old one. Only moves about half a degree between full hot and full cold. Not sure how to go about testing the signal sent by the controls.

-Justin

Just a though, make sure you can operate the blend door manually. It could be that it's got some trash in there that's keeping it from moving properly.
 

Rick Can

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I have been having a problem of Hot Air blowing out of the passenger front vents when the A/C is turned on. If I would switch to the heat setting, and then go back to cold setting, heat would still blow out of the vents even tho I could hear compressor working. Have had this problem for a year now, and asked on this forum but nobody new the answer, n some people had same problem, so thought I would help anybody out who may have this problem.

Well I flushed my radiator today and had to turn the heat on high to flush and fill radiator. When I turned the switch back to cold and turned A/C on, still hot air was blowing out of vents. It is way too hot in Arizona to not have Airconditioning!!! So I finally figured out what was the problem and here it is.

It is a faulty Air Mix actuator or Blend door actuator.View attachment 103816

It is located on the passenger side floor board under the dash.If you have the hush panel it will need to be removed using 7mm socket.View attachment 103817

Next you will disconnect the wiring harness and remove the two 5.5mm screw heads.View attachment 103818
View attachment 103819
View attachment 103820
After both screw are removed, the rear one is alittle difficult to get to so I just used the socket itself. The actuator itself should just pull right down, may be alittle tricky if fully in stop position.View attachment 103821

I purchased a new actuator, and just reinstalled back into vehicle. You will want to make sure the door is positioned the same as the actuator by moving the arm in the vehicle, NOT THE ACTUATOR. DON'T ADJUST ACTUATOR ITSELF, LEAVE THE WAY YOU PURCHASED. Mine was set in the cold.View attachment 103822

If you buy a new actuator, you need to make sure the part numbers match because they make many different styles of of these actuators for different vehicles and climate controls. Mine may differ from yours so don't base my part number on what you need to buy.

Now here is the tricky part that I had to research. Thanks to a site called Sparky's Answers, I was able to figure this all out and pass it onto everyone here. Very good information recieved, and very thurough. So I am going to use some of his information so everyone will be informed correctly.

Now supposedly if you have a scan tool you can adjust and calibrate the actuator thru the scan tool. Since I don't, he also gave information on how to calibrate without a scan tool. So here ya go.

First once you get actuator, new or used, make sure it can not move( I mean the metal know shouldn't be able to move by hand and diffenently don't move with pliers), if so, it is probably bad, if not go ahead and install the way it comes, and reconnect wiring. Then you will disconnect the battery for atleast 30 seconds. Then reconnect battery, turn the ignition to the ON position for atleast 1 minute, but he suggested 3-4 minutes so that's what I did, and DO NOT TOUCH THE A/C CONTROLS!!! You will then turn ignition to the OFF position for atleast 10 seconds, then start the engine and confirm the new actuator is working correctly by turning the climate knob from cold to hot. If all was done correctly it will work!! I checked the actuator by being on the passenger side, turning ignition on, moving climate knob, and sticking my head under dash to watch for the actuator to move.

SUCCESS!!! Hope this write up helps anybody with this same problem. Any questions please feel free to ask, and I will do my best to help. If I missed anything, or miss typed, very sorry, my kid is trying to help write this!! LOL
I have been having a problem of Hot Air blowing out of the passenger front vents when the A/C is turned on. If I would switch to the heat setting, and then go back to cold setting, heat would still blow out of the vents even tho I could hear compressor working. Have had this problem for a year now, and asked on this forum but nobody new the answer, n some people had same problem, so thought I would help anybody out who may have this problem.

Well I flushed my radiator today and had to turn the heat on high to flush and fill radiator. When I turned the switch back to cold and turned A/C on, still hot air was blowing out of vents. It is way too hot in Arizona to not have Airconditioning!!! So I finally figured out what was the problem and here it is.

It is a faulty Air Mix actuator or Blend door actuator.View attachment 103816

It is located on the passenger side floor board under the dash.If you have the hush panel it will need to be removed using 7mm socket.View attachment 103817

Next you will disconnect the wiring harness and remove the two 5.5mm screw heads.View attachment 103818
View attachment 103819
View attachment 103820
After both screw are removed, the rear one is alittle difficult to get to so I just used the socket itself. The actuator itself should just pull right down, may be alittle tricky if fully in stop position.View attachment 103821

I purchased a new actuator, and just reinstalled back into vehicle. You will want to make sure the door is positioned the same as the actuator by moving the arm in the vehicle, NOT THE ACTUATOR. DON'T ADJUST ACTUATOR ITSELF, LEAVE THE WAY YOU PURCHASED. Mine was set in the cold.View attachment 103822

If you buy a new actuator, you need to make sure the part numbers match because they make many different styles of of these actuators for different vehicles and climate controls. Mine may differ from yours so don't base my part number on what you need to buy.

Now here is the tricky part that I had to research. Thanks to a site called Sparky's Answers, I was able to figure this all out and pass it onto everyone here. Very good information recieved, and very thurough. So I am going to use some of his information so everyone will be informed correctly.

Now supposedly if you have a scan tool you can adjust and calibrate the actuator thru the scan tool. Since I don't, he also gave information on how to calibrate without a scan tool. So here ya go.

First once you get actuator, new or used, make sure it can not move( I mean the metal know shouldn't be able to move by hand and diffenently don't move with pliers), if so, it is probably bad, if not go ahead and install the way it comes, and reconnect wiring. Then you will disconnect the battery for atleast 30 seconds. Then reconnect battery, turn the ignition to the ON position for atleast 1 minute, but he suggested 3-4 minutes so that's what I did, and DO NOT TOUCH THE A/C CONTROLS!!! You will then turn ignition to the OFF position for atleast 10 seconds, then start the engine and confirm the new actuator is working correctly by turning the climate knob from cold to hot. If all was done correctly it will work!! I checked the actuator by being on the passenger side, turning ignition on, moving climate knob, and sticking my head under dash to watch for the actuator to move.

SUCCESS!!! Hope this write up helps anybody with this same problem. Any questions please feel free to ask, and I will do my best to help. If I missed anything, or miss typed, very sorry, my kid is trying to help write this!! LOL
 

Rick Can

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One side note to this.. Until you replace or repair the actuator, you can usually turn off and on the motor and it will go back to cold when it does the reset. It also helps to keep the temp set to the lowest setting so the computer doesn't try to reposition the blend door and it stays on full cold.

Mine is currently in need of attention, but being lazy, I just work around it for now. So I'm quite experienced at restarting when needed.

The cause of the problem is the position sensor in the actuator (a variable resistor) is dirty and not making good contact. While I havn't done it myself (yet) I've seen it said that you can open and clean that resistor and it'll work fine again.

My '05 Tahoe has the center console that goes under the dash. Does all that housing have to come out to get the actuator?
 

Sam Harris

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Just a though, make sure you can operate the blend door manually. It could be that it's got some trash in there that's keeping it from moving properly.
I have had this problem since I picked up my '03 Yukon a couple months ago. I ordered, and easily replaced the HVAC Control Module, though it was hard to find, and about $80 from Summit.
Unfortunately, after replacing, I still had only hot air in the rear HVAC unit. I found the blend actuator door is broken, and there is a large piece inside the unit. Unfortunately, I can't seem to find the replacement part handy. I found: 15-5717, but this part seems to be listed for only the Yukon XL, and I don't want to order the wrong part. (I already wasted $80 on the module that was not the problem!) I also had to take the entire unit apart, and there's always that one bolt that prevents you from getting it done right... I have one that attaches the rear of the auxiliary HVAC unit to the body, right in the back of the unit, and access is from underneath. I got a long extension on there, but it seems to be just spinning the bolt and nut. Getting the pieces lined up in the unit, while still in the vehicle appears to be an impossible task..
 

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