[Alan43]

On cold days (days below 60º outside temperature), my Acadia Denali 2021 environmental control system, set to warm the cabin to 75º blows cold air into the cabin, according to dealership infrared temperature readings between 5 and 10 degrees below the temperature set on either of the two the in-dash reostats. In short, my Acadia, which should be blowing warm air according to the in-dash temperature settings, blows cold (airconditioned) air, not heated air. There have been a number of times where I have had to set the cabin temperature to 80º, and still, I still experience airconditioning air coming out of the vents, and it's not until I raise the temperature to 82º plus that warm air starts to flow. GMC has taken the position that since there are no fault codes, the system is working correctly, and therefore there is nothing wrong. At the same time, the front seats experience blowing cold air when they should be blowing warm air, the second and third-row seat occupants experience blowing air in line with the lower settings on the rear controller. I contend either the temperature gauge or the thermister controlling the cabin heating/cooling system isn't working, but I can't sell that idea to my dealership to check. I need help - has anyone experienced this type of issue, and what was your solution?

 

[Cyynder]

Sounds like your thermostat is stuck open. I had that problem on my 2008 acadia, ran fine but heater at best would only blow slightly warmer air. I replaced the thermostat and problem was solved

 

[Alan43]

That's what I'm thinking, but trying to convince my dealership is a real problem. Seems GMC puts great store in the ability of their firmware to fault isolate problems and failures in their vehicles, and if a fault code doesn't appear, they've taken the position that there is no problem. I could be wrong, but I feel that the thermister or the temperature sensor aren't part of the fault algorithm. I'm just hoping others who read my inquiry respond, so I have a preponderance of similar situations to prompt my dealership to investigate the possibility that the temperature sensor or the thermister may have failed and effect a solution so that I'm not driving in a constant state of airconditioned cold air.

 

[Cyynder]

Thats why i just changed it myself, wasn't too difficult. I'm sure there are differences since yours is 13 years newer but still don't think it's too difficult. Search some videos online on how to do it, might be worth looking into

 

[Alan43]

Good point - thanks

 

[bxd20]

What happens if you set the heat ALL the way to max, 90 degrees? If it’s still blowing luke warm then perhaps it’s the engine thermostat.

Engine coolant temp has a gauge - what is it reading?