HVAC control unit

Tiny
KEVNLKING
  • MEMBER
  • 1994 GMC SIERRA
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
The AC/heat control unit keeps flashing when turned on sometimes it stops. Is it the head unit or the blend door actuator?
Friday, June 22nd, 2018 AT 8:23 AM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
It is flashing is trying to tell you a code can you count the flashes?

Please let me know. Cheers, Ken
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Saturday, June 23rd, 2018 AT 1:53 PM
Tiny
KEVNLKING
  • MEMBER
  • 26 POSTS
What does this mean?
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Sunday, June 24th, 2018 AT 3:23 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Thanks for the video! This usually means you have a mode actuator that is not working. Here is a guide to show you what you are in for when doing the job and the location of the actuator for your truck below:

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

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken
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Monday, June 25th, 2018 AT 11:13 AM
Tiny
KEVNLKING
  • MEMBER
  • 26 POSTS
Is this considered manual or automatic controls?
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Sunday, July 1st, 2018 AT 10:05 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
It says they are the same for either. Have you tried to replace the actuator?
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Monday, July 2nd, 2018 AT 11:55 AM
Tiny
KEVNLKING
  • MEMBER
  • 26 POSTS
Not yet, they were asking me if my unit is manual or automatic which I think is manual.
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Monday, July 2nd, 2018 AT 12:02 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I am Danny.

Your application/unit is manual. Hope that helps.
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Tuesday, July 3rd, 2018 AT 3:58 AM

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