2013 LTZ HVAC Mode door actuator Issues

[STU22]

on my 2013 the mode door actuator will move withot input from control. I have verified that the mode doors move freely and that it is not a mechanical issue with the mode doors. No matter what setting the HVAC control is in Defrost,feet face hot or cold or any combination the system wiil work properly for about 5-10 minuets, Then it moves with out any input to a netural type setting or open between mutiple positions where there is no air flow at all. The fan motor still blows at selected speed. The only thing that seems to be diffrent is if i have the AC on recirulate with fan on max speed it will works without issue,However is the fan speed is slowed down within 5 minuets or so the condtion will return. I have checked all of the blend door actuators and verified proper operation mutiple times. I have replaced the mode door actuator twice both with GM OE parts. I have reset both or cablirated manualy( dont have a tool to do electronically) Has anyone else ran into this issue?

 

[mikez71]

Check for codes?

I had a somewhat similar issue, it was with manual hvac controls.
My codes were

B0433 61
- Temperature Control 3 Circuit Actuator Out of Range / Stuck

B3782 61
- Air Flow Control 10 Circuit Actuator Out of Range / Stuck


My rear mode and temp would somewhat work, then the temp would not work at all, and the mode was incorrect.
Unplugging the battery would usually let it work initially for a few seconds before it quit working.
Looking at my Tech2, the commanded and actual positions were not lining up, and moving in opposite directions.
Ended up being a bad HVAC control unit. Got another off ebay to fix mine.

 

[swathdiver]

on my 2013 the mode door actuator will move withot input from control. I have verified that the mode doors move freely and that it is not a mechanical issue with the mode doors. No matter what setting the HVAC control is in Defrost,feet face hot or cold or any combination the system wiil work properly for about 5-10 minuets, Then it moves with out any input to a netural type setting or open between mutiple positions where there is no air flow at all. The fan motor still blows at selected speed. The only thing that seems to be diffrent is if i have the AC on recirulate with fan on max speed it will works without issue,However is the fan speed is slowed down within 5 minuets or so the condtion will return. I have checked all of the blend door actuators and verified proper operation mutiple times. I have replaced the mode door actuator twice both with GM OE parts. I have reset both or cablirated manualy( dont have a tool to do electronically) Has anyone else ran into this issue?

Might be time for a new controller. Really need to get a Tech-2 on it and see what's going on inside and pull the BCM codes for it, if any.

 

[STU22]

I did replace controller with a known good one no change in problem.

 

[mikez71]

Weird one...

so fan on high, everything works normally?
not on A/C and recirc both and it works?
Auto or manual controls?

There is no reset procedure in the Tech2 that I know of, sounds like the unit should calibrate itself..

Also, might want to test the known good control unit once more.
I remember working at a shop. customer drove in. the boss took out a new performance electronic distributor that was in that vehicle.
After work was done (days/weeks later), he put it back in. No work. He questioned my wiring.. no issues. Swapped distributors, works!
The distributor died just sitting in his office!

 

[Fless]

Might be time for a new controller. Really need to get a Tech-2 on it and see what's going on inside and pull the BCM codes for it, if any.

^^ This. Compare the commanded positions to the actual positions with a bidirectional scanner.

 

[swathdiver]

There is no reset procedure in the Tech2 that I know of, sounds like the unit should calibrate itself..

There is under special functions. The unit kind of calibrates itself with each key on but the Tech-2 recalibrate is the most effective. I've never been successful doing it manually.

 

[STU22]

Weird one...

so fan on high, everything works normally?
not on A/C and recirc both and it works?
Auto or manual controls?

There is no reset procedure in the Tech2 that I know of, sounds like the unit should calibrate itself..

Also, might want to test the known good control unit once more.
I remember working at a shop. customer drove in. the boss took out a new performance electronic distributor that was in that vehicle.
After work was done (days/weeks later), he put it back in. No work. He questioned my wiring.. no issues. Swapped distributors, works!
The distributor died just sitting in his office!

i put known good control in other vehicle and works fine.

 

[STU22]

i put known good control in other vehicle and works fine.

Automatic control

 

[mikez71]

So control unit works in another vehicle, but not yours?

Might need to find someone with a good scanner as previously mentioned..

Odd that it varies depending on blower speed.
So if you wait ten minutes and turn the blower to low, there's no problems?

 

[STU22]

So control unit works in another vehicle, but not yours?

Might need to find someone with a good scanner as previously mentioned..

Odd that it varies depending on blower speed.
So if you wait ten minutes and turn the blower to low, there's no problems?

I can stop and turn the vehicle off. let it sit for a while say 30 minuets start up and all will be fine for an hour or so. I have left the vehicle running and observed the mode door actuator moving to comanded poditions with no change. I have verified that the recirculation door is working properly. I have verified that the blend doors are not the cause. I have removed the actuators and tried to manually recreate the condtion with no luck. I do not have much of a scanner but it does not show any codes in the hvac or body control sections.

 

[mikez71]

I wonder if the doors are self adjusting due to the numerous temp sensors?
Looking at the diagrams, I see 5 temp sensors up front.
Left/right floor duct, left/right panel duct, and front passenger air temp. Perhaps one of the sensors are not reading properly?

Or your scanner is unable to read all available codes? idk...