Having an issue with my 2021 Tahoe where the A/C blows warm in the driver side front only. Passenger side front and rear are good and cold. First thought for me was this must be a blend door issue. The blend door does work at least partially because it goes to from warm to hot but never cold. I’m a heavy duty diesel technician and have plenty of experience with blend door issues and thought I’d try and figure this out before it gets too hot here in Texas. I removed enough of the dash to get to where I could see both the passenger and driver side blend doors actuators. I removed the driver side actuator and used my hand to turn the blend door in both directions but still going from hot to warm. Did the same on the passenger side and it goes hot to cold. Scratching me head at this point. The only thing I can come up with is that maybe the blend door itself is broken or something is in the way of it being able to close all the way. Really just looking for more information on how the automatic climate control works. I used Snapon scanner from work to recalibrate the blend doors but there is no change. Are there separate blend doors for hot and cold? Any help is appreciated.
2021 Tahoe A/C blowing warm on driver side.
- Thread starter DanJanson
- Start date
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Joseph Garcia
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Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
@swathdiver may be able to provide you with some perspective on the blend door system and troubleshooting procedures.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
@swathdiver may be able to provide you with some perspective on the blend door system and troubleshooting procedures.
stick a camera up there and check it out, manually moving the door should make it work 100%
2021nightmare
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I'm having this exact issue right now. My 2021 Tahoe was in for service because of the rear differential grinding and had them troubleshoot this issue to faulty programmable temperature valve actuator. They were going to replace it for a lot more than I was willing to pay.
Figured it out eventually. For some reason when the a/c system charge gets low, it causes the system to cool less on the driver side and the last section to be effected is the passenger side. 
weirdest thing I’ve seen on an a/c system. Put a can of 1234yf in it and it started cooling again. Found rear evaporator leaking. Replaced and now have a working a/c system again.
weirdest thing I’ve seen on an a/c system. Put a can of 1234yf in it and it started cooling again. Found rear evaporator leaking. Replaced and now have a working a/c system again.Thanks updating what you found. I have plenty of GM Blend door experience for the 1999-2006 GM models across the board. Have had to replace countless blend door motors and more often than faulty blend door motors, the problem was the female terminals in the connectors to the blend door motors would get loose and need to be tightened up so the blend doors would not knock and would fully travel when commanded. Not much experience with the newer chassis.
I also know from my BMW days, then the refrigerant gets low the same type of problem happens when the drivers side does not cool as well as passenger.
Not looking forward to dealing with the 1234yf systems.
I also know from my BMW days, then the refrigerant gets low the same type of problem happens when the drivers side does not cool as well as passenger.
Not looking forward to dealing with the 1234yf systems.
viven44
Full Access Member
Don't blame you. When our 2018 Tahoe's AC condenser developed a leak and had to replace it I spent $200 in 4 cans of R1234yf.... 4 cans of R134a would have been $32 from Walmart.
Meanwhile the 2500/3500HD truck owners still enjoy the use of R134a, even on 2025 year model trucks.
Having this same issue in my 2021 Yukon. I have a few questions:
1. Doubeleive said "stick a camera up there and check it out, manually moving the door should make it work 100%" Where do I stick the camera? And how do I manually move the door?
2. DanJanson said that adding refrigerant helped. I take it that I need cans of 1234yf for my 2021 Yukon? It has the 5.3, if that makes any difference. Can someone point me to instructions on how to fill the system? I tried it once on a 2004 Mercedes but never on a GM product.
Finally, I do think the drivers side cools down eventually but it takes a while. Does that sound more indicative of a blend door or low refrigerant?
Thank you for any responses!
1. Doubeleive said "stick a camera up there and check it out, manually moving the door should make it work 100%" Where do I stick the camera? And how do I manually move the door?
2. DanJanson said that adding refrigerant helped. I take it that I need cans of 1234yf for my 2021 Yukon? It has the 5.3, if that makes any difference. Can someone point me to instructions on how to fill the system? I tried it once on a 2004 Mercedes but never on a GM product.
Finally, I do think the drivers side cools down eventually but it takes a while. Does that sound more indicative of a blend door or low refrigerant?
Thank you for any responses!
