HVAC problem with UAS upgrade in '18 truck

I have an '18 Tradesman 2500 diesel on which I've upgraded the radio from RA1 to RA2 to RA4. I've also upgraded to the single zone push button HVAC with 7 speed blower, all using harnesses from M2 Mods. I ran the RA4 for a bit and am now trying out an '18 UAS (non-nav).
I really like most of the radio features and especially the improved sound quality. To me it is much better than the RA4, especially on HD radio.

The problem I'm having is with the temperature control with the UAS radio. I noticed today that I had very little heat, although the small icon on the upper LH of radio and the slider icon on the Climate screen both showed the arrow all the way up on red. My coolant temp was also at 192*. This didn't make sense to me as it worked fine with the RA4. After doing some investigation, I found that the blend door servo wasn't moving all the way to heat, it was only about half way.
In other words, the radio shows full heat, but the blend door is only halfway thru its travel between hot and cold.
The only way i can get the blend door to move all the way is to hold down the physical button (up arrow) on the dash for a few seconds. I played around with it for a while and noticed, too, that the servo lacks a little traveling to full cold.

For troubleshooting purposes, I reinstalled the '17 RA4 and everything matches up perfectly. Move the Climate temperature slider icon up to full red, and the blend door servo moves full travel in one direction. Move the slider to full blue, and the servo moves full travel in the other direction. It matches up everywhere in-between as well.

Any ideas on what could be causing this? It seems to be some sort of communication/calibration problem with the UAS radio. I've already ruled out the HVAC controller/module on the right side of dash, the HVAC/radio bezel, and the servo motor/actuator on the blend door, as they all work fine with the RA4.

Is there some sort of recalibration procedure or learning process that I can do? What about my Ram dealer? I called my friend that works at a local Ram dealer and he is going to check for me.

Mike @Mpgrimm2 and I have discussed it and we're hoping there's a calibration process that may fix it.
I have to give a lot of thanks to Mike for all the support so far. He's a standup dude and heckuva nice guy to boot!

Any input from the other gurus on this? @CuylerTech @DeereGuy

I have a similar issue with mine too (UAS). The indicator on the unit will show cold and it still blows hot air. I have to hold the physical button down a bit then it goes to cold.

I called Infotainment and they suggested I disconnect the battery, let sit for 15 minutes, then reconnect. It didn't fix it.

Hope you figure this out, I have just lived with it.

Update:
The issue is sometimes corrected by installing the 2018 HVAC module (sometimes) or the ATC Temp & Humidity Sensors/wiring (ATC seems to consistently fix it with either module. ** 14-19 classic 1500's get the additional humidity sensor)

8/27/20 EDIT: 19 Classic 1500 warlock with same issue starting at Post 133. (Single Zone ATC programming steps/reset also).

See post 6 further down....
As well as our M² mods vendor thread, the ATC thread and the UAQ/ UAS upgrade thread for additional info.

Here's a video of the Temp Slider issue on Gibb's truck when it does occur with a UAx radio upgrade.

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Updated link: https://youtu.be/DVQ6H1Dr9HM
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And here's what it should look like...
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Updated link: https://youtu.be/88m6JxwnxTk

Guido2112 said:

I have a similar issue with mine too (UAS). The indicator on the unit will show cold and it still blows hot air. I have to hold the physical button down a bit then it goes to cold.

I called Infotainment and they suggested I disconnect the battery, let sit for 15 minutes, then reconnect. It didn't fix it.

Hope you figure this out, I have just lived with it.

Click to expand...

Thanks for the info, man. Hate to hear you're having problems, but also glad I'm not the only one.
I disconnected the batteries for about 30 min and it didn't fix it, either.

Stuff like this drives me crazy...

I also reached out to Benny @AllMoparParts.com to see if there is an updated/different HVAC control module for the 2018 trucks

I will be curious what PNs he has for the various 18 trucks/trims. Still seems like a calibration/relearn but can't know without trying a few things one at time to eliminate them.

It's interesting that it works correctly (differently) with the 17 radio (minus the service cell error message you were getting), which verifies the 8.4 conversion harness and xxxx5017AE module are good imo (& DeereGuy). But the we are all essentially using a 13-17 module with the 18 radios. And the rest of us w/13-17 trucks & UAS or UAQ radio also have the Single zone ATC mod, and use the "Auto" temp function a lot.

- Mpgrimm2: 13Ram1500, 18 UAQ, Single Zone ATC mod/bezel (xxxx5017 module for 4spd)
--> Replaced: 18Ram1500, Factory UAS w/Dual Zone ATC & 68366552AA module

- DeereGuy: 16Ram2500, 18 UAQ, Single Zone ATC mod (xxxx5017 module for 4spd)

- 00R/T: 13Ram1500, 18 UAQ, Single Zone ATC mod/bezel (xxxx5017 module for 4spd)

- Rick's Ram: 14Ram1500, 18 UAQ, Single Zone ATC mod/bezel (xxxx8186 module for 7spd)

- STecoD: 15Ram1500, 18 UAQ, Single Zone ATC mod/bezel (xxxx8186 module for 7spd)

Edit/updates:

- 61N150W: 14Ram1500, 18 UAS (CA), Single Zone MTC, w/ xxxx8186 = No issues !?!

- Gibbs: 18Ram2500, 18 UAS, Single Zone MTC (issues w/ xxxx5017 fixed w/2018 68366553AA module)

- Guido2112: 17Ram1500, 18 UAS, single Zone MTC, (issues w/ xxxx8186 fixed w/2018 68366552AA module)

- jdip: 14Ram1500, 18 UAQ, Single Zone MTC, (issues w/ 68183973ab [alt for 8186] & 2018 68366552AA module. Other issues with radio v21.9)

- ckleinfeld: 15ram1500, 18 UAQ, Single Zone MTC, (issues w/ xxxx8186 & 2018 68366552AA module. Fixed w/Sgl Zone ATC mod)

- 8Banger: 14ram1500, 18 UAQ, Single Zone MTC, (issues w/ xxxx8186 & 2018 68366552AA module. Fixed w/Sgl Zone ATC setting until mod is complete)

Updated Summary:
Adding Single Zone ATC feature/wiring seems to consistently fix the temp slider/blend door issues seen in above posts with UAx radio upgrades.


M² Mods.

Agreed, and still waiting to see if my friend at Ram dealer has any insight on it. I'm not super confident because they were told they a radio swap wasn't even possible in these trucks. He seemed impressed with the radio conversion in my truck and brought out another tech to check it out. I guess officially they aren't allowed to support such a thing...

Gibbs said:

I also reached out to Benny @AllMoparParts.com to see if there is an updated/different HVAC control module for the 2018 trucks

Click to expand...

So there are new module part numbers for the 2018s. 1500 is part number 68366552AA and 2500 is 68366553AA. There have been new modules throughout the MY years, but the tried and true ones have always worked the best. It is possible that they changed something in the new modules to work better with the new radios. I will be completely honest, I have had the Single Zone ATC mod done if my truck for a good while now, so I never tested the UAx radios in my truck using manual temperature control.

Its probably important to note that the new part numbers do not show backwards compatibility with pervious year trucks. So whether they would actually work in a pre2018 truck, is a big question.

DeereGuy said:

So there are new module part numbers for the 2018s. 1500 is part number 68366552AA and 2500 is 68366553AA. There have been new modules throughout the MY years, but the tried and true ones have always worked the best. It is possible that they changed something in the new modules to work better with the new radios. I will be completely honest, I have had the Single Zone ATC mod done if my truck for a good while now, so I never tested the UAx radios in my truck using manual temperature control.

Its probably important to note that the new part numbers do not show backwards compatibility with pervious year trucks. So whether they would actually work in a pre2018 truck, is a big question.

Click to expand...

I have a 2018 truck, but still not sure if another module would do anything different. I have a friend with a 2018 Laramie 2500, but he's in Tennessee, and even if he was here, I'm not sure if he'd like me disassembling his truck to test parts, lol.

Deereguy and others, if you take your HVAC out of "Auto" mode and use the temperature up and down arrows, will you look and see if the servo is travelling fully according to the temperature indicator on the radio? Also, when you push the up or down arrow, does the indicator
skip up or down quickly? On the UAS, it skips or jumps up or down very quickly, instead of a small amount at a time on the RA4.


Here's some pictures for clarification:

This is the servo motor on the LH side of opening with glovebox removed





When the indicator is showing full cold, the actuator is almost in full cold position (down), but not quite





When the indicator is showing full hot, the actuator is only about halfway thru its travel, so not letting much heat by. It should be all the way to the top stop.

I appreciate ya'lls support on this. This makes me bang my head on the wall...

Gibbs said:

I appreciate ya'lls support on this. This makes me bang my head on the wall...

Click to expand...

Can you take a short video of the skip and send it over to @Mpgrimm2 or post it here. We have seen skipping before when converting from MTC to ATC. I just want to see if yours is exhibiting the same behavior.

I run my truck with auto off a lot and have never noticed any problems. My slider is smooth. There is however a difference in BCM settings between MTC and Single Zone ATC.


Sent from my iPhone using Tapatalk

I emailed @Mpgrimm2 a short video of it. Hopefully he can see what I'm talking about. It only takes about 6 presses of the arrow to move the pointer full scale in either direction. On the RA4, one press only moves it a minute amount

Gibbs said:

I emailed @Mpgrimm2 a short video of it. Hopefully he can see what I'm talking about. It only takes about 6 presses of the arrow to move the pointer full scale in either direction. On the RA4, one press only moves it a minute amount

Click to expand...

Uploaded to my YouTube channel for everyone to see...

http://www.ramforum.com/index.php?posts/1458159]M² Mods.

Appreciate that Mike

Benny responded and said there was a different control module for the 2018s, confirming what @DeereGuy mentioned earlier. He also said that he looked on the service side and there is a calibration procedure for the HVAC. I will update as soon as can talk to my friend at the Ram dealer.

DeereGuy checked various 18 Ram 1500 & 2500/3500 with 8.4 radios (4c), Single & Dual zone, verified by picture in PA (About 60) against TechAuthority by vin and I also checked the 6 dealers in my area (SC) to double check for 18 HVAC module PNs. Here's the basics once again ...

- 18Ram1500, MTC Sgl Zone : 68366552AA module

- 18Ram1500, ATC Dual Zone : 68366552AA module


- 18Ram2500, ATC Dual Zone : 68366553AA

* 18Ram2500, MTC Sgl Zone : ???
(neither of us could locate any verified trucks. Not sure if they exist)

As DeereGuy stated, it appears that...
- 68366552AA = 1500 trucks w/8.4 radios (MTC & ATC)
- 68366553AA = 2500/3500 trucks w/8.4 radios (ATC)

Cost for each is in the $120-$130 range.


http://www.ramforum.com/index.php?posts/1458159]M² Mods.

Thanks for all the research, guys; much obliged for all the time you put into this. I'm blown away by your generosity!

I'm supposed to go by the dealer tomorrow evening and see if we can figure something out on the calibration. This truck just seems to be the right combination of things where nothing works 100%.

If that doesn't work, it's either live with the issue, try out a different module, or reinstall the RA4. I'll burn that bridge when I get there, lol. Wish I had a newer module to try out, wouldn't take 10 min to swap in...

Well, no bueno with the calibration. It was cool to see, though. Plugged in wireless dongle into OBD, went into laptop and performed the calibration process. I watched the blend door servo go through its entire travel.
We discussed sales codes and HVAC modules. He's going to see if he can find a module from an 18, but not holding my breath.
I think the module might be the answer (or at least the next logical step) but right now I can't afford to buy one and risk it not working...

This may be the push that makes me put the RA4 back in. I have some thinking to do...(dangerous!)

@Gibbs
Email sent.

http://www.ramforum.com/index.php?posts/1458159]M² Mods.

Received. Thank you kindly, Mike!

On another positive note, one of my best friends agreed to let me remove and try out the 911/Assist rearview mirror from his '17 Laramie 3500 to see if it will remedy the 911 error with my RA4 radio. I may try it out this weekend. Anybody have any special tips for removal? I sure don't want to booger up or break any parts on his new truck!