No climate control again

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Tmssteve

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I have a 2015 2500 diesel with factory 8.4 unconnected. 2 years ago the heat would not turn on. It was locked out in both the screen and buttons. Took to dealer they replace the climate module. Last week same thing happened climate won’t turn on from the controls no heat no defrost no heated mirrors. I order a new module and replaced it (behind glove box). Nothing. I know this is what they replaced last time because the date code is 2019. I tested voltage and get the 12v, I disconnected the batteries overnight but still nothing. Does it need to be programmed from the dealer or should it be plug and play. I made an appointment at the dealer but they are 4 weeks out. Any thoughts?
 

Hemi395

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Do you have access to a scan tool that can read all the modules on the truck? You will need to be able to access the HVAC module to pull the codes in that module. Hopefully its not the actually 8.4 Uconnect unit....
 

Jeepwalker

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First I would start by feeling the heater hoses/pipes going to the heater core (engine warm). Feel if they're both hot to make sure it's not a faulty engine thermostat. Make sure the coolant is up to full. Could be a faulty heater vent door too. Sure it might be a hvac controller, but usually problems are small things ...or at least look at the small things first. Dealer might have 'thought' it was the controller last time, but then after installing it, turned out to be something else. How often does that happen?! Well guess, what they're probably not inclined to remove it, esp if they replaced multiple things and they weren't sure if it was a controller or not (sometimes controllers can be intermittent). They're just going to say it was the controller when it 'may' have been a $20 vent motor that was also replaced. Or maybe in your case it WAS the controller.

You could probably use AlfaOBD software (see 4th Gen DIY Forum) to scan yer truck and HVAC to get the codes and run it through it's paces (articulate vent doors, etc). Or another scan tool with good capabilities. As far as I know they don't need to be 'paired' with the main computer ...but I guess I'm not 100% sure. With a good scan tool there should be a 'cycle' mode where it'll run the motors through their range. If something doesn't move, then you'll know it's faulty.

Is the system acting (now) the exact same way it was acting before you installed the controller?
 
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Tmssteve

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Yes no change. You can go to climate screen and press on but it just ignores me. Same as pressing the buttons below the screen
 
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Tmssteve

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My scan tool says lost communication with HVAC module. When I try to access that module it errors out errors on radio and back says lost comm with HVAC.
Tested cam voltage at HVAC module connector and I get 2.5 volt on each line (I think one was green and one was white) 12v on red and 12v on pink all to ground (black) of connector
 
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Tmssteve

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Sorry auto correct bcm module not black

Also had various faults on drivers door passenger door
 

GTyankee

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You should know that your radio is called an Infotainment System
The radio itself is a minor part of it. It is mainly a 2nd computer.

Why do you have a non working radio ?

Which HVAC Control unit do you have ?

1642297191511.png

1642297390404.png
 
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Tmssteve

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2nd picture. Radio works fine (except climate screen) can press and hold temp up and down to access menus
Only 15 more days without heat until it goes into dealer
 

Slipknotjester

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2nd picture. Radio works fine (except climate screen) can press and hold temp up and down to access menus
Only 15 more days without heat until it goes into dealer
Do you have an update? I am having the same issue currently. My climate screen does not respond to the “on” button. Also, manual controls are non responsive as well.
 

GTyankee

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Slipknotjester

do you have the controls like in image #1 ?

If you do, your system will do a self calibration

something about pushing 2 of the knobs for something like 5 seconds, release then press again

someone may have the proper way to do it
 

Ktriky

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any update on this? 2015 ram 3500 with 8.4. Same issue and had the dealer replace climate control module 2 months ago. Based on my research the drain plugs clog and drip on it. Now it’s doing the same thing and drain plugs are clear. Scanning cannot connect to module. I can easily replace the control module but would like to know if something else is going on.
 
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