Whats up with the heat in the new GM's?

[Tcwhite]

I have an 07' Gmc yukon slt. I cannot figure it out. I can have the heat on and set at 90, but if I take it down a notch to 89 it feels lukewarm. Is this normal or is just me? I took it to the dealership today and dropped it off for them to look at that and an oil change. After three hours I went back to pick the yukon up the technichian sat in the car with me and went thru the different temps starting at 83. He said that he had reprogrammed the unit and tested it with a temp gauge and it was correct but it was still blowing cool air. I gave up and left. My friends Tahoe is warm at 80 and so is my dads suburban. What gives. I'm just looking for some relief here. Just seeing if anyone else is experiencing this or someone who could guide me into the right direction. I don't know if the system is faulty or if it just me getting used to the new Gm's. I'm used to Acura vehicles and never had a problem with ac/heat. Thanks!

 

[Rollin Thunder]

i run in to that to, is nice and warm at 90 but its too hot, but if i go to 87 it gets almost cold. :crazy: :mad2:

heat is the one and ONLY thing that i always have trouble with in this truck, and whats silly is if it was not digital id keep it at 90 or 60 because i just want it warm or cold, thats how it was in my 99, twist one way for warm twist the other way for cold, but now i go to 70 for air and 80 for heat, but i have trouble with the rear heat and controlling the front heat, the air is AWSOME, but heat is hard to get used to, thankfully i only use heat when its night time because it gets in to the sixties, in the day time its 90s so i use air.

 

[Rafael]

The heat seems to be almost like radiant heat. If I turn the heat on and set it at 80 it seems to blow cool, but it does get warm inside after a few minutes, weird, but it works.

 

[OSU_Tahoe]

Does the heat feel 'cold' only once the previous set point has been reached? What I'm wondering is if you set the temperature to 80 and the heater reaches that point and then you reduce the set point to 78, then by default the air that's being blown has to be cooler in order to move it from 80 to 78. The temperature of the air that's being blown is in relation to the existing temp in the vehicle. Setting it to 80 when it's 90 in the car will make it blow cold, but the same 80 set point will make it blow hot if the inside temp is less than 80. I'd also guess that the temp of the air being blown will be affected by how far from the existing temp that the new set point is. So it might blow hotter if you set it to 80 when it's 55 in the car than when it's 75 in the car.

GM might also have it programmed to find a compromise between getting to the set point in a reasonable time vs. the noise caused by the HVAC fan blowing at max speed. My wife has the same frustration in her Mercedes too.

 

[Rollin Thunder]

i think that only works on AUTO, when you control every thing it should blow what ever temp you have set.

 

[johnebgoode]

Are you sure you took it out of A/C mode by turning off compressor? There is a switch for the A/C compressor, it should look like a "Snow flake" or a star. Make sure it is off. If it is off and you're still experiencing problems, go thru manual thoroughly to make sure everything is correct, then call customer relations.

 

[Tcwhite]

Does the heat feel 'cold' only once the previous set point has been reached? What I'm wondering is if you set the temperature to 80 and the heater reaches that point and then you reduce the set point to 78, then by default the air that's being blown has to be cooler in order to move it from 80 to 78. The temperature of the air that's being blown is in relation to the existing temp in the vehicle. Setting it to 80 when it's 90 in the car will make it blow cold, but the same 80 set point will make it blow hot if the inside temp is less than 80. I'd also guess that the temp of the air being blown will be affected by how far from the existing temp that the new set point is. So it might blow hotter if you set it to 80 when it's 55 in the car than when it's 75 in the car.

I think this is what it is. I will wait till it gets a little bit cooler outside maybe in the morning going to work. I do have the ac off which is the snowflake button. Thanks guys for the quick response. I thought it was just me.

 

[Rollin Thunder]

well not for me, i have mine off, mine is different as i have an 06, yours looks like the one on my moms acadia,

here is what mine looks like ON!!!, I DO NOT RUN HEAT LIKE THIS

THIS IS HOW I RUN THE HEAT, NOTICE THE SNOW FLAKE IS NOT ON THE SCREEN, it is still cool, not cold, it just does not feel like 80, it feels like 70 on vent, it gets SUPER hot on 90m but 87 and its COOL, like i say it feels like 70 with out the snow flake.

 

[johnebgoode]

Rollin......your way is the correct way to use the heat.......!!

 

[Rollin Thunder]

i called the number from the gmc website and they said we have no idea talk to your dealer, they say thats how its supposed to run i wanna say :fu: but i know thats un professonal i tell them, how is setting the temp at 87 and it blowing 70 how it is supposed to work, i bought a temp sensor by the way, and they just kinda BS'ed me and i have an appointment with another dealer on friday, will see. i told them theres somthing wrong with my front heat because to get any heat from it at all i need it set to 90 and if i go to even 89 it gets a ton colder and i checked today it went to 74 when i set it to 89, i set the back to 82 and that pipes out the perfect temp, nice and warm but not so hot you wanna open the windows the whole ride home. I wish the front worked like the back, its funny how the back was not working at all when i first got the truck and now it works perfect, hmm maybe the messed somthing up with the front when they fixed the back.

 

[Tcwhite]

I'm with you rolling thunder as I think it is just BS. Anyways I went by the GMC dealership and after I told them about the problem with the heat they said it might need reprogramming. I told them that the chevrolet dealership down the road did that last week. They then said that it might be some actuators that might have gone bad and need replaced. I'm going to take her in this week or weekend and get it looked at since it is covered under warranty. I'll keep everyone posted.