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Heater problem?

Tiny
ALAN RAY
  • MEMBER
  • 1991 GMC C1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
Instead of one indicator arrow, it flashes all arrows. The blower motor works fine. 1 year old thermostat, radiator and reserve full. Not sure if the problem is in the heat) air control module (OEM board) or one of my three actuators?
And how can I tell where and which is the problem?
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Wednesday, October 19th, 2022 AT 7:26 AM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi Alan,

Are you able to control any of the functions? Also, the controller head had issues years ago. I remember a service bulletin where it would lock up causing the actuators to continue getting power and start clicking. The only fix was to replace the controller head.

Let me know if you have any control and exactly what is happening in addition to the lights flashing. Also, 16149268 is the original equipment part number. See pic 1 below for confirmation.

Take care,

Joe

See pic below.
Image (Click to make bigger)
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Wednesday, October 19th, 2022 AT 6:49 PM
Tiny
ALAN RAY
  • MEMBER
  • 4 POSTS
Thank you, Joe. I do not hear any clicking in the actuators. Cannot control anything on the operating heat/air display panel.
By controller head, do you mean the OEM board/module?
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Thursday, October 20th, 2022 AT 4:23 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

It's the control unit I attached a pic of above. If you can't control the temperature or the airflow direction, that is what it sounds like has failed. Also, I found a newer part number, 16143956.

Let me know.

Joe
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Thursday, October 20th, 2022 AT 6:23 PM
Tiny
ALAN RAY
  • MEMBER
  • 4 POSTS
Thank you sir.
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Friday, October 21st, 2022 AT 2:55 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Allan,

You are very welcome. If you have a chance, let me know how things turn out for you. Also, please let me know if there is anything I can do to help.

Take care,

Joe
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Friday, October 21st, 2022 AT 8:29 PM
Tiny
ALAN RAY
  • MEMBER
  • 4 POSTS
Got it working. It was the module board. My son, a Spartan school graduate and good with this type of stuff, cleaned and re-soldered a bunch of suspect areas. Blowing hot, just in time for winter.
Thanks Amigo.
Who knows, you may not have seen the last of me.
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Tuesday, October 25th, 2022 AT 4:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

I'm glad to know you got it taken care of. Also, please feel free to come back anytime in the future. You are always welcome.

Take care,

Joe
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Tuesday, October 25th, 2022 AT 6:28 PM

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