05 Yukon Denali heat problem

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#14951 Closed 2005 GMC Yukon Denali XL public

Hi Sparky!..I have a 2005 yukon denali xl with a duel climate control hvac system. This is my first winter with this vehicle and I’ve been having a couple issues with my heat/climate control…

It started off as no front heat at all (rear worked fine) so flushed the front heater core and that got me blowing hot again. The next issue was when I had the heat turned all the way up on both sides (90°), or in auto mode the driverside temp actuator would continuously switch between full heat and cold and the passenger side would stay ice cold.. I have some actuator experience with my 03 Suburban so I did a recalibration of the system. I attempted this several times until finally the driverside stayed hot constantly but it has to be set below 90°, if i go up to 90° it goes back to switching continuously between hot and cold. The passenger side now seems like a mix of hot and cold, staying luke warm.

So basically the driverside is perfect at 89° setting or lower or in auto mode but the passenger side is blowing luke warm at best.

Does this sound like a bad passenger side temp actuator to you or is it possible that the quirkness that I’m experiencing on the driverside is related? As in AC controls?

It may also be worth noting that the passenger side temp control knob doesnt always react properly. The temp jumps around sometimes and will often need to be turned very slowly to acheive the desired number..

Thank you for your time..


You likely have more than one problem. I assume you do not have a scan tool for the system so you will need to do some inspection and may have to change some parts to solve the issues.

The driver’s actuator is most likely the cause of the cycling issue at a 90 setting but I would recommend disconnecting, inspecting and reconnecting the harness connectors at the actuator and at the passenger side junction block. Then recalibrate again and check the operation. If that does not correct the problem then I would replace the actuator. You could try cleaning the circuit board and the contacts on the back of the inner most gear. There are two different designs. One you can clean and the other you cannot. You would not know until you open up the actuator.

The passenger side issue could have several causes. I would suspect that you have a partially clogged heater core since you had no heat at all until you flushed the heater core.  The best thing to do would be to remove the vent assembly to the right of the radio and look to see if the actuator is responding to commands. If it is then the odds go up that the heater core is partially restricted. If it does not respond to commands then the actuator may be faulty or the problem with the driver’s side actuator may be locking the system up and preventing it from working.

The problem with the display jumping around as you rotate the temperature knob is annoying but will not affect the operation of the system as long as you can reach the desired setting. Also it is  an issue inside the control panel.

Hope this helps.

Thank you for your response..

I failed to mention in my first post that before recalibration of the system I did remove the drivers temp actuator and clean the terminals and contacts on the large gear. They were pretty gummed up with lubricant.. that being said, yesterday the problem of continuous switching from hot to cold on the drivers side had returned for the day.

I dont have a scan tool to read as deep as hvac so I took it to a friend who scanned it for me.. it showed codes for faulty drivers side and passenger side temp actuators…

I’m going to inspect them again today, especially the passenger side being as i haven’t gotten into that one yet.. I’ve seen videos of possible access through the glove box and ac vent to the right of the radio… I want to rule out the heater core as my culprit being as i have the new info of actuator codes thrown… may even flush it again for good measure..

Are automatic and manual temperature actuators different from one another?.. pricing at the parts store goes from $50 for manual actuators to $150 for automatic. Can i use a manual actuator on my system and use it manually only? Or will it simply not function at all with my system?..

Also if i were to replace with automatic do you have that part number?.. I’ll likely order them rather than pay full retail at the parts store and want to make sure I’m ordering correctly.

Again, thank you for your help and time.


Something that you need to be aware of is that the relation of the inner gear with the contacts need to be fairly close to the corresponding position of the outer gear that has the drive shaft on it. What I always do after gently wiping the grease off of the contact surfaces is to gently bring the tension back into the wiper arms by lifting them away from the gear. Next the wiper contacts need to be centered in the travel area. Then when the outer gear is installed it needs to have the notch in the shaft aligned with the center hash mark on the outside of the case.

I always use the ACDelco brand actuator part number 15-72971. It is the correct actuator for the temperature doors on either manual or auto systems in your model truck. The best price on it right now seems to be on Ebay at about $60.

If you are going to be removing the actuators anyways I would recommend turning the door shafts by hand and seeing if the temperature responds correctly. If it does your heater core is okay.

Write a reply

The ticket has been closed. If you feel that your issue has not been solved yet or something new came up in relation to this ticket, you can re-open it by clicking this link.