HVAC issues...

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Okay, I have posted several threads concerning this issue in hopes that someone could shed light based on the troubleshooting I have already accomplished.

I will try and recap what I have done and what the issue(s) is/are:

Problem: 2013 RAM 1500 Laramie Factory 8.4 Automatic Temp Control
HVAC vents incorrectly responding to soft keys functions. Meaning, if I select defrost, the air will only blow out of face vents. Air will blow out of all the vents, so it is NOT a blend door actuator issue. With the battery reset and HVAC module reset, the HVAC functions work correctly until I hit either the defrost only or the defrost and feet soft key. If I select either of those via soft key they will only emit air from the face vents. Now, the kick in the proverbial nuts, if I try and select the feet vent soft key, for example, it still blows out of the face vents, even though I know it previously functioned correctly. Basically, once the HVAC function goes *****, I cannot go back to any setting. It just keeps blowing out the face vents. Unless, I turn off the truck, disconnect the HVAC module wiring harness (for about 10 seconds or so) and plug back in. I then have to turn the key to run (with out starting engine) and listen for the calibration noises of the blend door actuators. Once the calibration is complete, I can then start the motor and select the HVAC function I need (with the exception of defrost or defrost/feet) as indicated previously.

So, what the heck controls the signal/function of the HVAC system? The PCM, the radio, the HVAC module, a combination of everything???
---------------------------------
Parts replaced:
Been to the dealership twice with no solution from them
New Radio (8.4)
HVAC Module
Blend Door Actuators
Integrated Stack Control (Hard Keys below radio face)
-----------------------------------
I have yet to purchase an Alpha OBD, but it is on my list.

Anyone have any additional thoughts or methods to try to resolve this issue?

dh
 
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darleyhavidson
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Update: Had the heater core replaced, while the dash was pulled out I had local mechanic install an OEM blend door actuator that is next to firewall. After assembly the HVAC issues still existed, one of the Dorman brand replacement blend door actuators failed. Replaced with an OEM BDA and lo and behold the HVAC control issues were rectified. Unfortunately, I cannot definitively say what the issue was. If I had to guess it was the firewall BDA, that I could not access to replace, that went bad. I tested the Dorman brand BDAs after they were installed and they functioned like they were suppose to, but somewhere along the line, one failed. At any rate, after months and thousands of dollars, I finally have heat, when and where I want it.

Oh, and never, ever, ever use a dealership for non-warranty work. They literally have no idea on how to troubleshoot problems, if the diagnostic tool doesn't tell them what the issue is, they are blind. They literally were guessing and asking me to purchase parts that may or may not fix the problem. And they failed to tell me that the purchased (based on their recommendation) electric/electronic parts were non-returnable once used (even though it was determined the part was not the problem). And this was based on their "expert" troubleshooting skills. If you can't do the repair yourself, find a local mechanic that is trusted, you will be better off in the end.
 

Hilderman85

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Hey Darleyhavidson,
Having a similar issue to what you had, to clarify, are you saying that a single BDA failing can throw off the entire HVAC system?
 
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darleyhavidson
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Hey Darleyhavidson,
Having a similar issue to what you had, to clarify, are you saying that a single BDA failing can throw off the entire HVAC system?
Yes, basically. I can't substantiate the "how". But the failed BDA at firewall, once replaced, caused the 8.4 screen HVAC controls to work/respond correctly. I did everything else to try and fix the original issue, this was the last ditch effort. Been working correctly for the last 30,000 miles.
 

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