Multiple HVAC Sensors Bad?

[Jellybean Cowboy]

Hi all,

2020 RAM 1500; trying to diagnose abnormal HVAC behavior so I connected my OBD reader, fired up AlfaOBD and I'm getting the following codes from the HVAC module:
B11C8
B1030
B11F2
B11F1
B11F3
B11F0
B11C8

These codes are all associated with temperature sensors, either in the ducts for the panels, or the floor, as well as the evaporator. Some are reported as hard fault and some intermittent. Seems awfully strange and coincidental to have all these sensors go out at the same time. Seems more likely that I have a short on a harness or simply that the HVAC control module is faulty, no? Where do I even find the HVAC control module to make sure I don't have a poorly seated connector?

Any and all help greatly appreciated!

Jon.

 

[jkm312]

What is the date of manufacture for your truck? Tell us little more about what you are driving.
Some of the earlier builds, the AC is less than desirable.

 

[Jellybean Cowboy]

Sorry, manufacturing date is 10-19. The only modification I have made was to add rain sensing wipers with the alternate sensor behind the rear view mirror. HVAC worked just fine for quite some time afterwards (over a year and a half). Other than that, she's a stock truck.

 

[jkm312]

It's well known that some of the 19's have some AC problems. Most of it concerns the linkage to the blend door in the plenum. It doesn't close and lets the hot air mix with the cold air, does not cool the truck very well. The TSB is to tear out the entire dash to get to the plenum and change out the linkage. Some here have had that successfully done. Others have simply closed off the hot water in the warmer months with various clamps or ball valves and avoided the above TSB. I have no idea what your codes mean or why you are getting them. A simple test would be to clamp off the hot water and see if the AC will cool as it should.
If you search "air conditioning" you will get a ton of posts, some of them are very informative. Sorry I can't be more help but my little brain does not begin to understand all of the electronics in these trucks.

 

[Jellybean Cowboy]

Thanks for the reply; I had heard about this issue, but mine does not appear to be that. This isn't just a case of the A/C not getting cold enough; it actively tries to cook me randomly...!
Having faulty temp sensors would explain that swing but not why they have all seemingly gone bad together.

 

[kapinallinen2]

Thanks for the reply; I had heard about this issue, but mine does not appear to be that. This isn't just a case of the A/C not getting cold enough; it actively tries to cook me randomly...!
Having faulty temp sensors would explain that swing but not why they have all seemingly gone bad together.

"The HVAC module is mounted to the right side of the HVAC housing, just forward of the blower motor"
All those DTC`s have one common possible cause, the HVAC control module, a poor connection? possibility.
You going after it? subscribe to Alldatadiy.

 

[Jellybean Cowboy]

Dang right I went after it! Thanks for the pointer on location of the HVAC control module @kapinallinen2.

So, I removed the plastic trim clips from the panel under the gee-love box and what did I see?!
I had to remove the control module so that I could get the connector to seat properly because it simply would not pull down straight.
Now I'm convinced it was like this from the factory since I purchased the truck used and it's never worked right, but I had kinda convinced myself it was normal from all the Internet peoples complaining how poor the stock AC performance is. Should have known better from the test drive with the dealer when they said the refrigerant needed topping up...

Cleared the DTC's and now all good. Yay!

Thanks again folks.