AC control panel issues/ problem

[havasulou]

My Dodge Ram 1500 AC control unit recently started acting up. When you power on the AC with the control panel button and then shut the car off, you have to turn the AC on every time as opposed to it remembering that it was on previously. It's an annoyance more than anything and you can't remote start the car and have the AC cooling the vehicle as it should. I was wondering if there was a CMOS battery seeing as when the car is shut off the control panel remembers for 15 seconds. After 15 seconds the AC button will not remember that it was on (luminate)

I have posted a short video showing how are you control panel is acting up.

2008 Dodge Ram 1500 AC control issue / problem

My Dodge Ram 1500 AC control unit recently started acting up. When you power on the AC with the control panel button and then shut the car off, you have to ...

youtu.be

thank you

 

[markabby]

mystery to me, but, you posted an excellent video, which most people never do when explaining a problem.

i'm sure someone will come along and figure it out

 

[Black-Wolf]

My Dodge Ram 1500 AC control unit recently started acting up. When you power on the AC with the control panel button and then shut the car off, you have to turn the AC on every time as opposed to it remembering that it was on previously. It's an annoyance more than anything and you can't remote start the car and have the AC cooling the vehicle as it should. I was wondering if there was a CMOS battery seeing as when the car is shut off the control panel remembers for 15 seconds. After 15 seconds the AC button will not remember that it was on (luminate)

I have posted a short video showing how are you control panel is acting up.

2008 Dodge Ram 1500 AC control issue / problem

My Dodge Ram 1500 AC control unit recently started acting up. When you power on the AC with the control panel button and then shut the car off, you have to ...

youtu.be

thank you

Two thoughts:

1st, what's your resting battery voltage (meaning - with the truck off, nothing powered up for at least 15 minutes)? If the voltage is below 10.5 volts, you probably need to replace the battery. The reason for this is there's a Voltage Stability Module that monitors the battery voltage and ensures that it doesn't get to low. If it detects that the battery is too low, it shuts off some circuits that are not critical to the truck when it's not running. If your battery is constantly low, go by any auto parts store and have them test the battery and the alternator. Verify both are doing their job.

2nd, there's a fuse that provides the above constant power to specific circuits. On my 2017, for the HVAC system, it's fuse #06. Check and make sure it's not blown.

 

[havasulou]

Thank you markabby, checked the battery voltage good 12.77 and there's no blown fuses. It almost acts like when the CMOS battery in computers went bad, the computer wouldn't remember the date. I was almost thinking maybe there was a CMOS battery in the AC control unit?

 

[Black-Wolf]

I know you're running a 2008 year model - I don't believe there's any sort of CMOS battery. What there is though - I think - is a latching chip - basically an EEPROM or similar that, as long as there is a trickle of voltage from the main battery, will stay latched at the last set of settings you set your HVAC to. While the 2017 is a full generation newer, you can take a look at the below wiring diagram and maybe it'll help - it doesn't get into the circuity unfortunately.

 

[truck2569]

Two thoughts:

1st, what's your resting battery voltage (meaning - with the truck off, nothing powered up for at least 15 minutes)? If the voltage is below 10.5 volts, you probably need to replace the battery. The reason for this is there's a Voltage Stability Module that monitors the battery voltage and ensures that it doesn't get to low. If it detects that the battery is too low, it shuts off some circuits that are not critical to the truck when it's not running. If your battery is constantly low, go by any auto parts store and have them test the battery and the alternator. Verify both are doing their job.

2nd, there's a fuse that provides the above constant power to specific circuits. On my 2017, for the HVAC system, it's fuse #06. Check and make sure it's not blown.

But if that fuse was blown the AC system wouldn't activate the AC system