Strange HVAC issue

jason99ws6

Original poster
Member
Dec 12, 2011
1
Hi guys..Im new here but i thought i would toss this out there and see if anybody has come across this before. i can find bits and pieces to solve a few issues but not all.

06' TB 4.2L

Of course, blower motor quit working. Hoping it was just the ac/htr control unit so i swapped that out. After doing more research i see more than likely its going to be the module (auto control).

Here is where it gets weird.

Swapped in a new controller with the right part number based on my design number. Of course, same results. no heat. Here is the problem. The outside temp guage constantly reads 103* and the ac button (snowflake) WILL NOT turn off. I read about resetting the temp by holding the 3 buttons down and it works UNLESS i turn the truck off. then goes right back to 103*. Even after driving about 50+miles i thought it might recalibrate itself. not so.

Old unit never had this problem when i took it out. Is there something special to get the controller to read right? I know it wont fix the blower problem but this is a whole other issue.


Thanks in advance!
 

plaen

Member
Dec 4, 2011
55
jason99ws6 said:
Hi guys..Im new here but i thought i would toss this out there and see if anybody has come across this before. i can find bits and pieces to solve a few issues but not all.

06' TB 4.2L

Of course, blower motor quit working. Hoping it was just the ac/htr control unit so i swapped that out. After doing more research i see more than likely its going to be the module (auto control).

Here is where it gets weird.

Swapped in a new controller with the right part number based on my design number. Of course, same results. no heat. Here is the problem. The outside temp guage constantly reads 103* and the ac button (snowflake) WILL NOT turn off. I read about resetting the temp by holding the 3 buttons down and it works UNLESS i turn the truck off. then goes right back to 103*. Even after driving about 50+miles i thought it might recalibrate itself. not so.

Old unit never had this problem when i took it out. Is there something special to get the controller to read right? I know it wont fix the blower problem but this is a whole other issue.


Thanks in advance!

My 02 did something similar, it would stick at 50 degrees, if I reset it, it would read -29 till I shut the car off, the back to 50. I ended up replacing the sensor in the grille, and it read the same, had to pull the fuse under the seat for it to reset. Could tell you which one cause I pulled all hvac fuses. If it read correctly on the old one, I would try resetting it by pulling the fuse, if that still doesn't fix it, maybe time for a new sensor, a whole 6.81 at the dealer.

Edit, also don't forget the recalibration process, turn the key to on, and wait 90 seconds, before doing anything. But be warned if you have a bad actuator, it could totally fail after pulling the fuse.
 

neelskit

Member
Dec 7, 2011
69
jason99ws6 said:
...Of course, blower motor quit working. Hoping it was just the ac/htr control unit so i swapped that out. After doing more research i see more than likely its going to be the module (auto control).

Take a look at this thread to troubleshoot your Digital HVAC Blower problem: http://gmtnation.com/f23/no-c-heat-501/


plaen said:
My 02 did something similar, it would stick at 50 degrees, if I reset it, it would read -29 till I shut the car off, the back to 50. I ended up replacing the sensor in the grille, and it read the same, had to pull the fuse under the seat for it to reset. Could tell you which one cause I pulled all hvac fuses. If it read correctly on the old one, I would try resetting it by pulling the fuse, if that still doesn't fix it, maybe time for a new sensor, a whole 6.81 at the dealer.

Edit, also don't forget the recalibration process, turn the key to on, and wait 90 seconds, before doing anything. But be warned if you have a bad actuator, it could totally fail after pulling the fuse.

:iagree:
 

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