HVAC issue

[Bigbrentp]

Greetings! New member here. I’m looking for some help on a hvac issue. I have a 2015 ram 3500 tradesman. Just had the actuators and blend doors done along with the cores and we have a new issue. When cycling between face vents and floor vents and back there are no issues. When going from defrost to floor and back there is also no issues but when going from face to defrost, it won’t switch hardly at all and when it does it won’t go back and the same when it’s on defrost it might switch to face vents but the majority of the time it will stay on defrost when the control is turned to face vents. If I turn my truck off with the vents on defrost then restart the truck after a minute or two, it will go to defrost and if I turn the knob to face vents while the truck is on and it’s stuck on defrost, I restart the truck and it will turn back on in the position the knob is in. We replaced the one actuator for those two functions and no change. Plugged a computer in and did the calibration and that actuator failed, I don’t remember the exact code but it was a communication issue. So it will switch but I have to restart the truck to get it to do so. Also through the computer, all of the doors would move while doing the test function through the OBD connection, except that one again. I’m trying to find some insight to determine if it is the hvac control module by the glove box or if it could be the control panel on the dash. It was not going this before the repairs. I’ve been told two different things, one being that if the scan tool was able to force move the other actuators by bypassing the dash controls then it could be the hvac control module but also that if the scan tool was able to communicate with the hvac control module at all then it’s fine ‍

 

[jws123]

When you replaced the actuators are you sure you used the correct ones/part numbers for each? I am sure others will reply its going to be something stupid for sure I know on the older rams you would hold down a button on the controls to do a calibration without the scanner not sure on a 15.

 

[Bigbrentp]

Yes we used the correct actuators and did the calibration on the ac controls and through the scan tool connected to the OBD

 

[GTyankee]

First of all .....................

The air will always go to DEFROST first when the engine is cold, it is made that way
The Windshield will clear FIRST

Hopefully whoever worked on the HVAC, they use MOPAR Actuators
not Dorman actuators, both work, but MOPAR actuators self calibrate, especially with the Control Module.

Did they check the different Doors that are inside the HVAC Box itself ?

Is your HVAC system a Single Zone or DUAL Zone ?

I believe this is a SINGLE Zone


then i think that this is a DUAL Zone


Believe it or not, i bought my Ram new, it was a Factory Order
I do not know if i have single or dual zone
But, i live right by Mexico

 

[Bigbrentp]

Update, I pulled the radio trim and accessed the actuator for the face and defrost. I pulled the actuator and cycled the dash control and the actuator moves multiple times to and from the two different positions without issue. As soon as I reinstall the actuator and turn the dash controls it will switch once then won’t move again…

 

[SnaggleToof]

I am having the exact same issue as you.

Vents would intermittently not switch from defrost to face. Randomly after certain startups it would work, but most of the time it does not.
I had a shop change all 4 actuators with new Dorman actuators. After this, basically nothing worked lol. Then they redid the installs with Mopar actuators. Everything calibrated fine and worked the day I left the shop.

Next morning, i cant switch to face again.....

2016 Ram 2500 with Dual Climate Control

 

[Bigbrentp]

Update. My issue continued with only the one actuator. After being told maybe it could be the hvac control module or maybe actuators not being OEM and blah blah blah. Did a bunch of research and discovered this, you all may already know but incase you don’t, here goes….

The manual ac controls with the 3.5-5’’ screen come in two options, a 4 speed fan and a 7 speed fan. The 4 speed fan dash controls are significantly more expensive…hmmm. So looking further, the hvac control module that is suppose to be on the passenger side behind the glove box was not here in my truck. My truck has the 4 speed fan dash controls. The 7 speed controls also only have 1 plug in the back of them to remove where as the 4 speed has two. Further research and talking to the dealer i learned that the 4 speed controls have the “control module” built into them where as the 7 speed controls have the separate hvac control module that is behind the glove box inside the dash, mounted to the far side. As well as the 8.4” screen has the same module in the dash behind the glove box. Just threw in a new “inexpensive” set of 4 speed dash controls and bam! All actuators are now moving as intended with no issues. I can only assume that the voltage signal to that one actuator from the controls was not enough and when it started working the doors it said it didn’t have enough power to fight the resistance. Use this as you will, it worked for me.