Rear heat door actuator location

Tiny
LIPS3185
  • MEMBER
  • 2017 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 50,000 MILES
My rear ceiling vents only blow out heat when the temperature is set to 90 degrees. If it is not set to 90 degrees it blows out cold are bit only from the ceiling vents. All other vents including the rear floor vents work perfectly fine. I am assuming it might be heat door actuator? I’m a correct in assuming this and if so where would be the location of this particular actuator location? Any help or assistance is greatly appreciated
Thursday, November 14th, 2019 AT 3:07 PM

11 Replies

Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

It sounds like you are having a problem with the auxiliary mode valve actuator.It's located on the right rear side HVAC box.Here is a basic tutorial showing how to replace blend/mode door actuators:

https://www.2carpros.com/articles/replace-blend-door-motor

You will have to remove right rear trim panel to gain access.After valve replacement you will have to perform a re-calibration. I've attached pictures below with location and instructions.Hope this helps and thanks for using 2CarPros.
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Thursday, November 14th, 2019 AT 3:35 PM
Tiny
LIPS3185
  • MEMBER
  • 12 POSTS
I pulled the panel and noticed there are two actuators back there I am waiting for the new one to come in. It should be the one closest to the passenger side door correct? What is the one most rear for?
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Thursday, November 14th, 2019 AT 5:10 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again,

Yes, I've re-attached picture and circled in red. It is the closest to the front. The one in the rear near (tailgate/hatch) Is a temperature control actuator. Hope this helps and thanks again for using 2CarPros.
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Thursday, November 14th, 2019 AT 5:27 PM
Tiny
LIPS3185
  • MEMBER
  • 12 POSTS
I swapped out the part with a brand new one tonight and did a reset. I noticed that the rear temperature follows what the driver temperature is set to. Not sure if this was an issue before to be honest and I just didn’t notice. For Instance if driver temperature is set to 72 and rear panel is set to 80, it will blow out at 72. Unless the rear is set to high it follows what the driver is set to.
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Monday, November 18th, 2019 AT 3:39 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Yes, I do believe they are controlled individually. Was it doing this the same way before the repair?Thanks again for using 2CarPros.
Danny-
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Thursday, November 21st, 2019 AT 4:05 PM
Tiny
LIPS3185
  • MEMBER
  • 12 POSTS
I honestly don’t know if it was doing it before the repair. It seems the rear controls don’t matter at all, unless it is set too high on heat then it blows out hot. Otherwise it blows out what the driver temperature is set to regardless what the rear temperature is set at.
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Thursday, November 21st, 2019 AT 4:17 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Depending on the ambient outside temperature it might take a little longer for the rear cargo (back) area to heat up due to the rear aux heat/AC unit box that includes the heater core take longer for the coolant to heat and reach that unit. Hope this helps and thanks again for using 2CarPros.
Danny-
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Friday, November 22nd, 2019 AT 3:11 PM
Tiny
LIPS3185
  • MEMBER
  • 12 POSTS
It does make sense however, it has been mid 70's outside and I tried it after the vehicle had been running for over 10 minutes with the same result. Rear ceiling vent blowing at the temperature that the front driver temperature is set to not what the rear control panel is set to.
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Friday, November 22nd, 2019 AT 3:39 PM
Tiny
DANNY L
  • MECHANIC
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Hello again.

Okay, I'll find out if there might be a control panel reset. Did you happen to disconnect the battery while performing the repair?
Danny-
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Saturday, November 23rd, 2019 AT 4:59 PM
Tiny
LIPS3185
  • MEMBER
  • 12 POSTS
I disconnected the battery after the repair for about 5 minutes.
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Saturday, November 23rd, 2019 AT 5:28 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

It usually a good idea to leave battery disconnected for 10-15 minutes. If you want to try and get back to me after if problem persists we'll go from there. Thanks again for using 2CarPros.

Danny-
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Monday, November 25th, 2019 AT 4:11 PM

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