How to Add Automatic Temperature Control (ATC) to a Manual Temperature Control Truck

[Ricks Ram]

Another time the AC will go into recirculation on its own is if you set the blower speed to 7. It did this before I did the single zone ATC conversion, I have yet to test this since.

Yes a lot of systems open the recirculation door on Max A/C or the highest fan speed when you have the A/C on but they will usually tell you it's on recirculate. My MTC system did that as well. What I'm referring to is it switches to recirculation on it's own in other scenarios and the actual LED on the recirculation button doesn't reflect what the actual setting it's on.

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[crash68]

Yes a lot of systems open the recirculation door on Max A/C or the highest fan speed when you have the A/C on but they will usually tell you it's on recirculate. My MTC system did that as well. What I'm referring to is it switches to recirculation on it's own in other scenarios and the actual LED on the recirculation button doesn't reflect what the actual setting it's on.

When mine was still MTC, if it switched to recirculation on its own it would not indicate that via LED or on screen. This was both temperature based and if I turned the fan to 7. The sound of the fan gave it away as I usually kept it on 4 or 5. Like you stated the recirc door could be overridden by hitting the button twice.
I think the switch to recirculation was possibly based on the differential between outdoor, evaporator temperature and/or where the temperature selector is se. It eventually stops recirculation on its own with no major change in OAT. It's just my $0.02 guess as the AC has always kept me comfortable.
I like having the ATC now but sometimes wish there was a way to speed up the fan without knocking it out of Auto mode.

 

[duunoit]

wish there was a way to speed up the fan without knocking it out of Auto mode.

On mine, lowering the temp seems to do that...

 

[crash68]

On mine, lowering the temp seems to do that...

I guess I needed to specify without changing the temperature set point.
Probably the better way to have stated it would be to have a selectable minimum fan speed in Auto mode.

 

[bellaireroad]

This is all great information, thanks


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[duunoit]

I guess I needed to specify without changing the temperature set point.
Probably the better way to have stated it would be to have a selectable minimum fan speed in Auto mode.

Like I always say at work... “trust the technology”.

 

[crash68]

Like I always say at work... “trust the technology”.

Funny you mention that, it's what I do. I program building controllers for AHUs that have upwards of 200 horsepower fan motors in them. I'm well versed on airflow and occupant comfort, you could say I write the technology. :-D

 

[Scottieone12]

I wanted to Thank @Mpgrimm2 and @DeereGuy for the harness to make the Atc work on my 2018 Ram 1500 radio upgrade to a 2018 UAQ radio. Mpgrimm2 went the extra mile with me on the Aplhaodb programming.

Thanks Again, I will post my pictures on how I did the whole upgrade.

 

[bellaireroad]

Can someone point me to the codes that need to be changed in alphaobd? Thanks


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[crash68]

Can someone point me to the codes that need to be changed in alphaobd?

Look on the first post in the AlphaOBD for everything you need to know.
https://www.ramforum.com/threads/alfaobd.123982/

 

[Mpgrimm2]

Can someone point me to the codes that need to be changed in alphaobd? Thanks


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Vehicle Configuration 3: HVAC Configuration:

Select:
Dual Zone ATC

Disconnect AlfaOBD app & shut off the truck for a few minutes and you must wait for the Dual Temp sliders to display on the 8.4 radio climate menu before proceeding with single zone ATC change.

** (Battery disconnect or pulling fuse near brake booster between changes can speed up the radio/BCM reset, especially with a UAx radio. Radio has read configuration when sxm button appears and Backup Cam displays again.)

Select:
Single Zone ATC


M² Mods.

 

[bellaireroad]

Vehicle Configuration 3: HVAC Configuration:

Select:
Dual Zone ATC

Disconnect AlfaOBD app & shut off the truck for a few minutes and you must wait for the Dual Temp sliders to display on the 8.4 radio climate menu before proceeding with single zone ATC change.

** (Battery disconnect or pulling fuse near brake booster between changes can speed up the radio/BCM reset, especially with a UAx radio. Radio has read configuration when sxm button appears and Backup Cam displays again.)

Select:
Single Zone ATC


M² Mods.

Thanks, do you have to tell it there is a humidity sensor?


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[Ricks Ram]

Thanks, do you have to tell it there is a humidity sensor?


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No, the truck will look for it automatically.

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[bellaireroad]

I wanted to Thank @Mpgrimm2 and @DeereGuy for the harness to make the Atc work on my 2018 Ram 1500 radio upgrade to a 2018 UAQ radio. Mpgrimm2 went the extra mile with me on the Aplhaodb programming.

Thanks Again, I will post my pictures on how I did the whole upgrade.

View attachment 176450

So I just got mine working. Was looking at the photo in this post, and noticed something similar on mine. Only differences it was 102° outside at 10 o’clock at night, not 92, as in the picture. Anyway I had it set on auto, at the lowest temperature possible, like in the picture, it didn’t seem like the air coming out was very cold, and the AC light was not on, just like in the picture. It was going to take a long time to cool the cabin down.

I flipped it over to AC and the air got much colder.

So how does this work? It seems with 102° outside, The air would be much colder until the desired temperature is reached.


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[Ricks Ram]

So I just got mine working. Was looking at the photo in this post, and noticed something similar on mine. Only differences it was 102° outside at 10 o’clock at night, not 92, as in the picture. Anyway I had it set on auto, at the lowest temperature possible, like in the picture, it didn’t seem like the air coming out was very cold, and the AC light was not on, just like in the picture. It was going to take a long time to cool the cabin down.

I flipped it over to AC and the air got much colder.

So how does this work? It seems with 102° outside, The air would be much colder until the desired temperature is reached.


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If it's 102° outside it should blow extremely cold if you have it in the lowest setting. It all depends on the actual temp inside your cab. Rule of thumb is these systems aren't that complicated in how they work. If your cab is 98° inside and you have your ATC set to 72° it's going to blow just as hard and just as cold until it reaches 72° as it would if you set it on LO. It should also be in recirculation mode. As it gets closer to 72° the fan speed will start to slow down and when the inside gets even cooler providing it's not to hot outside it will switch from full front dash outlets to dash plus floor. It is normal for the A/C button not to illuminate when you have the truck in ATC. Non of the LED's, fan speeds or blend door positions show up when the truck is in ATC mode. Drive it for a few days and see how it works. I keep mine between 72° and 74° in the summer and it seems to be perfect for me but everyone is different.

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[crash68]

I flipped it over to AC and the air got much colder.

So how does this work? It seems with 102° outside, The air would be much colder until the desired temperature is reached.

If when you flipped to manual AC, if the fan was slowed down or the system when into recirculation, that would explain why the air temperature would get "colder"
Not 100% sure how the ATC determines when to use recirculation but I'm taking an educated guess it's humidity/dew point related.

 

[Ricks Ram]

The truck goes into recirculation automatically when the truck is in ATC mode and the A/C is running on full dash vent. From the four trucks I have tested which two were factory ATC trucks plus my truck and STecoD's truck which have both been converted to Dual Zone ATC. All four trucks acted exactly the same. When you take it off if ATC the truck is sill in recirculation mode but the LED will not illuminate on the recirculation button. You need to push the button to illuminate the LED and then push it again to actually take it off of recirculate. I thought my truck was working incorrectly because it did this but it was identical to the two factory ATC trucks I tested so it appears to be normal. Long story short if it's hot outside and hot in your cab and you have your ATC set to the lowest setting the system should be running on full cold full fan on recirculate automatically. Another thing to note is if you have a tinted front window it may affect how the system works.

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[bellaireroad]

The truck goes into recirculation automatically when the truck is in ATC mode and the A/C is running on full dash vent. From the four trucks I have tested which two were factory ATC trucks plus my truck and STecoD's truck which have both been converted to Dual Zone ATC. All four trucks acted exactly the same. When you take it off if ATC the truck is sill in recirculation mode but the LED will not illuminate on the recirculation button. You need to push the button to illuminate the LED and then push it again to actually take it off of recirculate. I thought my truck was working incorrectly because it did this but it was identical to the two factory ATC trucks I tested so it appears to be normal. Long story short if it's hot outside and hot in your cab and you have your ATC set to the lowest setting the system should be running on full cold full fan on recirculate automatically. Another thing to note is if you have a tinted front window it may affect how the system works.

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Thanks Rick, worked great today, never have used ATC, takes a little getting used to. Not used to it being cool without the AC light on!
The only way I can tell if the recirculation is on, is if the light is on.

Roger



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[Ricks Ram]

Thanks Rick, worked great today, never have used ATC, takes a little getting used to. Not used to it being cool without the AC light on!
The only way I can tell if the recirculation is on, is if the light is on.

Roger



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Yes it's definitely a little strange. When the recirculation door opens you can hear the system get louder. If you want to hear the difference turn off the ATC and then just turn on the A/C. Push the recirculation button and the LED will turn on but you won't hear any difference because the recirculation door was already open even though the light wasn't on. Push the recirculation button again to turn it off and wait a second and you will hear the system get quieter. This is when the recirculation door closes and you go to outside air. You can then turn it on and off with the button and the LED will illuminate accordingly. Not sure if you are aware but you can have M2mods build you a custom Single Zone ATC bezel so you can turn the ATC on and off without having to go into your climate control screen. This is a picture of mine before I actually installed Dual Zone ATC.

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[BadAppleDeadHorse]

Sorry if this was already answered, I just couldn't find it.
I have a 2013 with the 8.4 mtc and I see that the "conversion" harness is mentioned. Do I need that if I already have the stock 8.4 or does this atc mod only work if I switch to the 2018 screen?
I would like to actually jump straight into dual atc like I saw in another post, but those instructions were for going from single zone atc to dual. Not from mtc to dual.

Thanks, and as a new ram owner, it's awesome to find such an awesome forum for people like me who have to open and modify everything they own.