Auto/Dual-Zone Air Conditioning Temp Knob Troubles

2021 TRD OR
Automatic/Dual Zone Climate

I’m having a bit of trouble with my climate control panel. I always use auto mode because I like to set the temp and let it do the rest. It works well.

Lately, the temps on the screen jump around some when I roll the knob. For example, if I’m on 70, and turn the knob one click, it will go to 71, then another click 72, etc, but then it might jump back to 70, or might skip from 75 to 78, etc. It’s mostly consistent, but randomly jumps around sometimes. Very irritating.

I am going to go out on a limb and guess I need a new AC control. But I’m curious if anyone has experienced this and what the fix was if so. Searching returns basically nothing that I can find.

Assuming I need a new AC control, does anyone have the factory part numbers? @Jeff Lange maybe? There are a bunch of part numbers for these and the part numbers are nowhere on the actual part that I can find, so no clue what to buy if this is the issue.

For reference, the model I have is silver, 4WD, auto climate, WITHOUT smart key. Pretty rare honestly because this one mostly comes on manual transmissions only and manual transmissions usually have manual, which leave me with slim pickings. I can find maybe one on eBay.

Thanks for any help.

 

Well, now this is going to turn into an educational thread. Pretty sure I just fixed the problem quite simply in just a few minutes.

I had this spare climate control I bought off of eBay a while back that does not have the 4WD knob, because at one point I planned to swap to a manual transfer case, where this control without the knob would be a clean OEM solution to deleting the knob. This control panel was just lying around so I decided to take it apart.

The knobs themselves are fully mechanical and rotate a gear driven rectangular piece which indexes into a sensor on a circuit board and rotates the sensor as you select the temp. Or maybe it’s a potentiometer, I dunno. This means physically the knob itself is just fine, and that the logic board is probably misinterpreting the sensor, or maybe the sensor is falsely reporting movements to the logic board.

It turns out that the automatic control panel logic boards are the same across the models (although I will say I’m not sure if heated seat models are the same - they might have their own additional connector or they could be integrated into the board since the buttons are right next to the screen).

This means the board is swappable, so I took the spare and put it into my truck’s control panel. Problem seems to be solved now. So if this ever happens, I’d just buy another of the cheapest auto non-seat-heat controller I could find off of eBay and swap the board again.

Take the 6 screws out:



Pull off the back cover. Gently pull the logic board out. It gets hung up on the hazard switch, so gently tug on that upper right corner to free it.



Swap the boards, reinstall the cover and it’s 6 screws. Reinstall into the truck.

 

If I recall properly when I had my AC control apart the solder pads for the seat heater buttons were present, just no buttons or the correct bezel. The buttons fed some traces I couldn't follow and upon viewing the schematics a LIN is used for the control.

It will be interesting to see if your problem is completely solved - time will tell. Mine is also a 2021 and I think I have been seeing similar errors in temperature selection. Myself, I will in my first attempt to fix, just take it apart and put it back together - seems to work quite often. I'll also look at the components the dials control to see if replacements are available.

The reason I had my AC Control apart was to bring clarity to the Hazard Switch by painting it red. I use the switch quite often.

 

That is actually probably correct for the seat heat buttons. I didn’t think to look when I had it open.

I think this will solve my problem - if not, then I would imagine the AC amp is the problem…but the control board makes way more sense as the problematic part. The way this goes together, I doubt taking it apart and put it back together will make any difference. Mainly because the part the knob drives just slips into a slot that turns the piece on the board. There’s not really anything that can get physically messed up - just seems like a part went bad.

Hope this doesn’t become something I have to do every 60K, but guess we’ll see.

 

All I can find on the knob potentiometers or whatever they are, is ALPS brand and 3 and 108. Both temp knobs use the same hardware.

 

Nice troubleshooting!

 

ALPS is certainly a manufacturer of potentiometers.

A 10,000 Ohm potentiometer would be labeled 103, for 10 plus three zeros for 10,000 ohms, or 10K Ohms.
The 108 I will guess is 1,000,000,000 for one Gigaohm. Seems a bit high, but I also don't know just what the manufacturer of the AC Control unit is doing with the continuously rotatable knobs.

I guess the above in italics is just for educational purposes as I found my pictures of the item in question and where your labeled as "103", mine are labeled "029".
Did not find any markings on the PCB of the maker; most modules I have opened on this truck are Continental, Denso or Toyota.

 

Instead of a potentiometer, it could be an encoder. Such as:
EC10E1220505 Product information | EC10E Series | Through shaft Encoder | Encoders | Products Search | Products & Technologies | Alps Alpine
This would account for the continuously rotatable knobs.

Found no directly comparable product on the ALPS website to our mystery component.

 

Just updating this to say that the circuit board from the eBay unit has fixed my issue entirely. I’ll fix it the same way next time too.