Heat works great in the front but blowing cold air in the back

Nancy Mintz · January 27, 2020

We have a 2019 Sierra and the heat works great in the front but blows cold in the back. Vents are open and we have it re—circulation - any ideas?

Belo · January 27, 2020

does it do the same with recirc off? I never have recirc on. What about in auto mode?

Snakes709 · January 28, 2020

mine does it too, poor design from GM

Edited January 28, 2020 by Snakes709

Troger · January 29, 2020

On 1/28/2020 at 11:16 AM, Snakes709 said:

mine does it too, poor design from GM

Same with 2019 GMC Denali. Unacceptable.

Taz56 · January 29, 2020

Mine too... 2019 AT4... Horrible.

Scarnag · January 29, 2020

Noticed this as well and it seems you have to turn on the rear heat for the vents to blow hot/warm. Seems stupid to me but maybe a way to separate the front and rear temps.

Taz56 · January 30, 2020

17 hours ago, Scarnag said:

Noticed this as well and it seems you have to turn on the rear heat for the vents to blow hot/warm. Seems stupid to me but maybe a way to separate the front and rear temps.

I don't have "rear heat" do you mean "rear defrost"?

AJMBLAZER · January 30, 2020

42 minutes ago, Taz56 said:

I don't have "rear heat" do you mean "rear defrost"?

Crew cabs have vents in the back of the front seat/center console for the back to get some heat directed Back there.

Taz56 · January 30, 2020

Just now, AJMBLAZER said:

Crew cabs have vents in the back of the front seat/center console for the back to get some heat directed Back there.

I know that and I have that. What confused me was he said "turn on the rear heat" how do you turn it on? I do not have a button or knob to turn it on and when I have all three going "defrost, center vents, foot vents" the heat "trickles" out the back. It is pathetic actually how bad it is.

oldmann · January 30, 2020

Have you tried center only in the front or floor only to see how the rear behaves?

Scarnag · January 30, 2020

@Taz56 Paid attention this morning on the way to the office. The rear heat button (defrost) does not make any difference as I thought it did when I did a quick test.

So the two little vents don't blow when floor only is selected, had to turn on main vents and did not mess with defrost.

They did blow warm air but the flow is not equal to the main vents so less air coming out.

It seemed like they took longer to blow warm air than main vents but not sure on that one.

AJMBLAZER · January 30, 2020

The air in the back is propelled down narrow and winding exhaust ducts by the same blower motor that does all the work up front.

The air will be lower in temp and with less velocity

Kickerz71 · January 31, 2020

The air in the back is propelled down narrow and winding exhaust ducts by the same blower motor that does all the work up front.

The air will be lower in temp and with less velocity

+1

nolte · February 1, 2020

My observation in 2020 Silverado CTB crewcab:

1. Rear vents really only push decent air when middle vents are selected (windshield and floor vents off)

2. Rear vents take a few moments to heat up even when truck is 'warm' and front vents are already blowing warm air.

Mine does blow warm air in the back, but not at first, and airflow is minimal unless middle vents are the only selected vent.

Taz56 · February 1, 2020

2 hours ago, nolte said:

My observation in 2020 Silverado CTB crewcab:

1. Rear vents really only push decent air when middle vents are selected (windshield and floor vents off)

2. Rear vents take a few moments to heat up even when truck is 'warm' and front vents are already blowing warm air.

Mine does blow warm air in the back, but not at first, and airflow is minimal unless middle vents are the only selected vent.

I tested yesterday and found the same thing. And that is crap. You have to sacrifice keeping your windshield and side windows from fogging up so the people in the back have heat? Not impressed.