Hot air coming from 4 front dashboard vents

[Mikey999]

Ive noticed when driving in temperatures  about 4 to 7 outside  sometimes when its sunny i just turn off the climate  control system but hot air  still  comes out from the vents even though sounds  like fan is off. This happens during longer drives at 80km per hour is this  normal? Is this a  heat from engine  coming through?

[JimCost2014]

1 hour ago, Mikey999 said:

Ive noticed when driving in temperatures  about 4 to 7 outside  sometimes when its sunny i just turn off the climate  control system but hot air  still  comes out from the vents even though sounds  like fan is off. This happens during longer drives at 80km per hour is this  normal? Is this a  heat from engine  coming through?

Question, does your AC still work? I know you have the fan off, but I do not think the system is truly ever off on these trucks.

Reason I am asking is, your condenser may have failed on you, very common problem on the early trucks and SUV's. 

[CamGTP]

Turn the temp down past like 72-73 degrees and I think it will close the hot blend door.

[davester]

Driving will push some air through the system even with the fan off, and if the blend door directs air through the heater core, you will get some heated air through the vents.

[George100]

I noticed too, when i am driving if i set the auto temp to 21 it may come out the vents as cool air depending on outside temp or heat. 22 auto is heat only either defrost or floor. When i turn off the auto, it stays at what ever temp it was set before turning off. If you dont want the heat just turn the knob to 15 or 16 and shut it off.

[Mikey999]

On 10/27/2020 at 7:57 PM, JimCost2014 said:

Question, does your AC still work? I know you have the fan off, but I do not think the system is truly ever off on these trucks.

Reason I am asking is, your condenser may have failed on you, very common problem on the early trucks and SUV's. 

Im going to check next time i drive  and let you know 

Edited October 29, 2020 by Mikey999

[Mikey999]

23 hours ago, George100 said:

I noticed too, when i am driving if i set the auto temp to 21 it may come out the vents as cool air depending on outside temp or heat. 22 auto is heat only either defrost or floor. When i turn off the auto, it stays at what ever temp it was set before turning off. If you dont want the heat just turn the knob to 15 or 16 and shut it off.

I have experienced  the same thing,  is this normal.  Why does this happen ?

[George100]

I have on all my GM vehicles, Caddies etc with the Auto climate control setting that 21 is the cutoff point between heat and cool air, its programmed that way. I guess that GM figures that nobody would set their climate control auto setting to 20 and expect any heat.