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

So Looking at some connector drawings on the dc tools mopar repair kit website the compressor clutch is actually controlled from the pcm I believe .
The HVAC module must send a signal to the pcm then the pcm sends the output .
I will connect to the pcm and see if I can see any HVAC stuff in there .

I don't have a copy of the schematics for any of the HVAC systems yet so I'm not sure what pin#s they are but I am hoping to find some soon. I am pretty sure you get the Sun Sensor DTC codes as soon as you do the full 8.4 upgrade even if you don't do the ATC conversion but I could be wrong. The thing that doesn't make sense is the sun sensor still works after the conversion so I'm not sure why it's showing two shorts. We pulled Nathan's out of the dash and it has 4 wires attached to it but since we don't have schematics yet we have no way to determine what they are exactly for. For whatever reason any time the system is on it is turning the compressor on by default no matter what setting it is on. I don't understand why the truck isn't throwing any codes showing that it's overriding my commands when I push the A/C button to turn it off. You would think that it would throw severaI codes if the system was opperating incorrecty. I also don't understand why the button will indicate that the A/C compressor has been turned on or off but it has no effect on the compressor whatsoever. In most cases with these trucks the button will blink a few times and then turn off if the command cannot be completed. I will get the part# he found for the other sensor and post it later. The more I think about the more confused I get. Non of it makes any sense.

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My truck at the moment is just set to MTC like if from the factory and the solar sensor errors don’t Exist .
I had a RA2 from factory and now the ra4
The faults for the solar sensor only Appears after the Atc flash has been done .
Here is the sun sensor connector

Oh that's good. I thought they showed up on my truck after the 8.4 conversion but I may have been mistaken. My truck also originally had the RA2 radio. That's actually good news. I don't understand how turning on the ATC code can cause it to show a short in the Solar sensor unless maybe the system is trying to get information from the solar sensor that it cannot get. Maybe the other solar sensor has more pins for other wires to connect to it to feed information to the HVAC module or it's just capable of feeding different information? I will try to get the other part number ASAP and post it. I sent him a message but I haven't heard back. I should have wrote it down last night but I didn't think about it. We were going to go ahead and order one just to see what it looks like. It might be the same exact sensor but they're only around $18 so it won't cost that much to find out.

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Unfortunately for whatever reason I can't see the picture you posted. I have tap talk and it sucks.

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I tried the pic again .
It’s a png format

ok I went on my computer so I could see them. That's interesting that it has a 4 pin setup just like our trucks do now. so basically its either the Solar sensors are actually different or we are missing something in the wiring for the HVAC module to read the sensor. This is the part number Nathan found for the other sensor. it is 68230114AB. I'm not sure if its an actual different sensor but it shows it has a different application and wont fit our trucks.

Since it is solar sensor that is "faulting", wonder if the fault goes away if it does not see light??
It would be a strange way to "read a sensor" to turn the AC on

I wonder if the Dual zone ATC trucks have the same HVAC module and the same solar sensor as our trucks

OK we pulled the sun sensor out of Nathan's dash and even though the plug going to it has 4 wires the sun sensor itself only has two pins. This means that two of the connections are not in existence which would cause us to get the DTC codes we're getting for right and left solar sensor feed. The part number on the solar sensor that's in Nathan's truck now is
68230115AB. This is one number off from the other sensor we found this shows it's for the different HVAC configuration which is part number 68230114AB. Hopefully that's Solor sensor would have the four pins and possibly take away the DTC codes we are getting now. I'm not sure if that will fix the air conditioning control issue but it's definitely a place to start. I am posting a couple of pictures of Nathan sensor now and you can see it only has two pins I will then post the different part numbers and the applications that he found. I'm going to go ahead and order a Sun Sensor and hopefully get it in a few days and see what happens.

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I can see if my dealer had the sensor on hand tomorrow.
If so I will try it out

That part number you had posted does have 4 pins. I am pretty sure that I have the same errors in my truck also. So I am not sure if this will lead us down the right path or not but it’s a good place to start. @WilliamS can you confirm if your factory 8.4 1500 exhibits the same problem since you converted it to ATC?

https://m.ebay.com/itm/CHRYSLER-200...447305&hash=item285b4a747a:g:TU8AAOSwNMVaaXtH

I think @00R/T was onto something with the humidity sensor: I found this on techauthority.

A humidity sensor (1) is used on Automatic Temperature Control (ATC) models to detect humidity levels inside the vehicle to optimize the dehumidifying effect of the A/C system. The humidity sensor is attached to a plastic sensor bracket (3) by a metal retaining clip (2). The sensor bracket is attached to the inside of the windshield by an adhesive. A cover (not shown) is attached to the sensor bracket by four plastic tabs (4). The humidity sensor is connected to the Body Control Module (BCM) by a dedicated three wire lead and connector that protrudes out from under the front of the headliner.


CAUTION:
Use care when servicing the humidity sensor. The humidity sensor bracket cannot be serviced separately from the windshield. If the sensor bracket becomes damaged, the windshield will need to be replaced.



The humidity sensor can be serviced without the use of any special tools.

The humidity sensor detects humidity, dew point and windshield glass temperature, and sends this information to the Body Control Module (BCM) over a Local Interface Network (LIN) data bus connection. The BCM then broadcasts the message over the Controller Area Network (CAN) data bus to the Heating, Ventilation and Air Conditioning (HVAC) module. The HVAC module automatically adjusts A/C clutch operation, amount of recirculated air, blower motor speed and outlet modes to prevent fogging on the inside of the windshield glass. If the humidity sensor message is not received by the HVAC module, a Diagnostic Trouble Code (DTC) will set. The information the HVAC module receives from the humidity sensor can be viewed using a scan tool.

I also compared a 2014 Laramie to a 2014 Express in terms of sensors. Here is what I found:

Yeah I'm definitely not betting on it making a difference but it's all we have to go on since it's the only DTC codes I have. I went to dealership and ordered it I'll have it tonight. He verified that that part number is the sun sensor for the Dual Zone system. There's a good chance that our trucks don't even have the proper wiring going back to the HVAC module or wherever it goes anyway because we've seen in the past how a lot of the wires in the lower trim levels just terminate and never really go anywhere. That being said I'm not even sure if it'll get rid of the DTC codes when I install it. I'm definitely curious to see if someone that has a 14 or newer 1500 that came with the 8.4 from the factory that upgraded to the ATC has the same symptoms we do. One thing to mention is they have to physically get out and see if the compressor stopped spinning because even though you push the button and it shows that it's off it's actually still engaged.

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DeereGuy said:

I think @00R/T was onto something with the humidity sensor: I found this on techauthority.

A humidity sensor (1) is used on Automatic Temperature Control (ATC) models to detect humidity levels inside the vehicle to optimize the dehumidifying effect of the A/C system. The humidity sensor is attached to a plastic sensor bracket (3) by a metal retaining clip (2). The sensor bracket is attached to the inside of the windshield by an adhesive. A cover (not shown) is attached to the sensor bracket by four plastic tabs (4). The humidity sensor is connected to the Body Control Module (BCM) by a dedicated three wire lead and connector that protrudes out from under the front of the headliner.


CAUTION:
Use care when servicing the humidity sensor. The humidity sensor bracket cannot be serviced separately from the windshield. If the sensor bracket becomes damaged, the windshield will need to be replaced.



The humidity sensor can be serviced without the use of any special tools.

The humidity sensor detects humidity, dew point and windshield glass temperature, and sends this information to the Body Control Module (BCM) over a Local Interface Network (LIN) data bus connection. The BCM then broadcasts the message over the Controller Area Network (CAN) data bus to the Heating, Ventilation and Air Conditioning (HVAC) module. The HVAC module automatically adjusts A/C clutch operation, amount of recirculated air, blower motor speed and outlet modes to prevent fogging on the inside of the windshield glass. If the humidity sensor message is not received by the HVAC module, a Diagnostic Trouble Code (DTC) will set. The information the HVAC module receives from the humidity sensor can be viewed using a scan tool.

I also compared a 2014 Laramie to a 2014 Express in terms of sensors. Here is what I found:

View attachment 131366

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That's definitely a great lead but I wonder why it's not throwing any codes at all?
I would have no problem installing a humidity sensor if I could get some schematics and even find out where the thing goes. To me the humidity sensor makes much more sense than the sun sensor because tne humidity sensor would activate the compressor whenever it detected humidity and possibly the compressor is on by default because it can't since the humidity level in the truck. I have tons of schematics but the only ones I don't have are the ones that relate to this and I've had a tough time trying to find them to try to figure this all out.

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Ricks Ram said:

That's definitely a great lead but I wonder why it's not throwing any codes at all?
I would have no problem installing a humidity sensor if I could get some schematics and even find out where the thing goes. To me the humidity sensor makes much more sense than the sun sensor because tne humidity sensor would activate the compressor whenever it detected humidity and possibly the compressor is on by default because it can't since the humidity level in the truck. I have tons of schematics but the only ones I don't have are the ones that relate to this and I've had a tough time trying to find them to try to figure this all out.

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Click to expand...

I would expect you’re not getting a code for the humidity sensor because the truck isn’t configured to look for one.

It mounts to the windshield to the right of the rear view mirror mounting post. It’s also used as the sensor for the auto wipers. I never installed one because it requires a different windshield that has a cutout in the blacked out area and a bracket bonded to it. If you’re just using it for the humidity portion, you might be able to find a way to rig it up to the glass. If the glass temperature isn’t super important and it only wants humidity and dew point, then it probably wouldn’t even need to be on the glass.

Ricks Ram said:

That's definitely a great lead but I wonder why it's not throwing any codes at all?
I would have no problem installing a humidity sensor if I could get some schematics and even find out where the thing goes. To me the humidity sensor makes much more sense than the sun sensor because tne humidity sensor would activate the compressor whenever it detected humidity and possibly the compressor is on by default because it can't since the humidity level in the truck. I have tons of schematics but the only ones I don't have are the ones that relate to this and I've had a tough time trying to find them to try to figure this all out.

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Click to expand...

As @00R/T said it is on the windshield. It needs 3 wires: LIN, Ignition Power, and Ground which it gets from the mirror jumper harness. The good news is that connector is sourceable and the harness is also available to purchase. The harness part number is: 68207371AB. Just have to find a good source for LIN if building a custom harness for it. The connector part number is 4-1718346-1. The other interesting thing is it looks like the 2500s and up do not have an option for a humidity sensor. I'm still researching this for sure though. IF it turns out to be true, this may help explain why mine works correctly also.

so where does the jumper harness make it way too ?
I’m looking at the bcm connectors online and don’t see any humidity sensor input etc .

skuppy069 said:

so where does the jumper harness make it way too ?
I’m looking at the bcm connectors online and don’t see any humidity sensor input etc .

Click to expand...

It doesn’t run back to the bcm. It splices into the Lin bus used in the mirror connector.

OK I installed the new Solar Sensor and there was no change in the HVAC operation. I didn't expect there would be But now we know. The two DTC codes did not clear themselves so I cleared them and try ed it again and it still didn't work correctly. I am going to code the truck again tomorrow after I drive it and see if the codes come back after I cleared them. If the DTC codes come back it will most likely mean that our trucks may not have the correct wiring running to the sensor. That being said Deer Guys truck and other 2500 and 2013 trucks seem to work fine even though it's got the sun sensor codes so I'm leaning more towards the humidity sensor now anyway.

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