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

[skuppy069]

Was there four wires at the connector ?

 

[Ricks Ram]

Yes there were. The connector looked right and the wires were the correct color but we have found in the past that on a lower trim level trucks part of the harness is there but the other part is missing so you never know if the wires are actually going to go where they belong or just terminate somewhere. A good example is the plug for the power inverter outlet. The wires don't go to the seat where they belong. They terminate at another connection under the dash. Deer Guy said it looked to him like the wires actually ran into the HVAC module in the schematics he was looking at for my truck so hopefully the codes won't come back tomorrow.

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[Ricks Ram]

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.

Do you it's probable that if I did install the humidity sensor that the system would pick up on it even though it's not looking for it or do you think there may be another setting in the BCM that's not flagged to look for it so the systems not operating properly?

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[00R/T]

Do you it's probable that if I did install the humidity sensor that the system would pick up on it even though it's not looking for it or do you think there may be another setting in the BCM that's not flagged to look for it so the systems not operating properly?

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There’s a setting that tells the truck the sensor is present.

 

[Ricks Ram]

Oh OK thanks that's next then. I'm going to get the harness and the sensor ordered and get it installed even if it's makeshift just to see if it helps.

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[WilliamS]

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 am checking to see if I can cycle the compressor in manual mode correct? If that’s the case I’m 100% certain I can as most of the spring that’s how I ran it. Just had it on outside air, turned to low and pulled in outside cool air with the compressor (a/c) button not illuminated. If this isn’t what you need let me know I’m happy to assist as always.

 

[Ricks Ram]

Yes on our trucks even when we push the A/C button to turn the A/C off in manual mode the light does not illuminate but the compressor is actually still running. Basically unless we have the system completely turned off the compressor is running all the time. I never realized mine was doing it until another member mentioned it and I went out and checked and saw that mine actually doesn't turn off either.

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[Ricks Ram]

I am checking to see if I can cycle the compressor in manual mode correct? If that’s the case I’m 100% certain I can as most of the spring that’s how I ran it. Just had it on outside air, turned to low and pulled in outside cool air with the compressor (a/c) button not illuminated. If this isn’t what you need let me know I’m happy to assist as always.

Can you put yours on manual and turn the A/C button off and open the hood to verify the compressor is not engaged when you get a chance? Im not sure why yours would act any different than the RA1, RA2 trucks but if it does it may help us figure this out. Ours will only disengage the compressor when we turn the system completely off . Also what year is your truck? Thanks.

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[WilliamS]

Can you put yours on manual and turn the A/C button off and open the hood to verify the compressor is not engaged when you get a chance? Im not sure why yours would act any different than the RA1, RA2 trucks but if it does it may help us figure this out. Ours will only disengage the compressor when we turn the system completely off . Also what year is your truck? Thanks.

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Will try tomorrow around lunch time, no way I’m going out in mosquito season! Also it’s a 2014 Bighorn.

Added auto climate using Deere harness, also added the heated/cooled seats and more but none of that should change the a/c behavior.

 

[Ricks Ram]

Ok thanks a lot I appreciate it we're just trying to get this figured out. I had no idea mine wasn't working correctly until someone else mentioned it and I ran it on vent all the time and didn't pick up on it but basically the compressor never quits turning it's always engaged. So far everyone who has checked that has a 1500 2014 or newer that has done the ATC conversion is having the same symptoms but they all started with RA1 or RA2 radios.

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[WilliamS]

Ok thanks a lot I appreciate it we're just trying to get this figured out. I had no idea mine wasn't working correctly until someone else mentioned it and I ran it on vent all the time and didn't pick up on it but basically the compressor never quits turning it's always engaged. So far everyone who has checked that has a 1500 2014 or newer that has done the ATC conversion is having the same symptoms but they all started with RA1 or RA2 radios.

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Wife decided we were driving her car into work today, she doesn't like my truck in drive thru's. So I might not get to this today, I dont get off till 4 and were going to a few houses for some shopping.

Also a side note, if there is a humidity sensor my truck will likely keep the compressor on, I am in Florida.

 

[Ricks Ram]

Wife decided we were driving her car into work today, she doesn't like my truck in drive thru's. So I might not get to this today, I dont get off till 4 and were going to a few houses for some shopping.

Also a side note, if there is a humidity sensor my truck will likely keep the compressor on, I am in Florida.

OK thanks for the update. If you physically turn the system to manual and turn off the A/C and just turn it to vent the compressor should stop running.

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[WilliamS]

OK thanks for the update. If you physically turn the system to manual and turn off the A/C and just turn it to vent the compressor should stop running.

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No matter the ac button illumination if the fans on the compressor is active on my truck. Bighorn with factory 8.4 and 7 speed

 

[Ricks Ram]

OK it sounds like yours is doing the same as the rest of the trucks that have the ATC mod. The compressor should turn off if you manually turn off the A/C and turn it to vent. This means our compressors are running pretty much all the time. We have compared the operation on our trucks to trucks that came with the ATC from the factory and the compressor on those trucks shuts off if you manually turn off the air conditioning and in some cases when the heater is being used. Thanks for the update it pretty much lets us know that it's not something involved with the actual 8.4 conversion for the lower trim trucks and we can rule some of that out and start focusing on other possible causes. Now that I've heard back from you I'm going to go ahead and order the humidity sensor and the harness and get it installed and see if that corrects the problem.

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[WilliamS]

OK it sounds like yours is doing the same as the rest of the trucks that have the ATC mod. The compressor should turn off if you manually turn off the A/C and turn it to vent. This means our compressors are running pretty much all the time. We have compared the operation on our trucks to trucks that came with the ATC from the factory and the compressor on those trucks shuts off if you manually turn off the air conditioning and in some cases when the heater is being used. Thanks for the update it pretty much lets us know that it's not something involved with the actual 8.4 conversion for the lower trim trucks and we can rule some of that out and start focusing on other possible causes. Now that I've heard back from you I'm going to go ahead and order the humidity sensor and the harness and get it installed and see if that corrects the problem.

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Although doesn’t affect me much here in Florida, do have the luxury of using ac all 12 months, but would be nice to kill it on those cool nights

 

[Ricks Ram]

Has anyone used the AE tool to go from the ATC mode back to MTC and if so did it cause the vehicle brand corruption like it does when we go from MTC to ATC with the AE tool? I'm just curious in case I end up putting my truck back to MTC if we're not able to figure out what's going on.

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[skuppy069]

I did and was okay .
I had only had problems when trying to go to atc with the AE

 

[skuppy069]

I got a new truck yesterday with dual zone and it has the humidity sensor on the windshield.
My guess is 0/RT is right on the money with the humidity sensor causing the problem.

 

[Ricks Ram]

I got a new truck yesterday with dual zone and it has the humidity sensor on the windshield.
My guess is 0/RT is right on the money with the humidity sensor causing the problem.

Yes I think he is. I'm thinking the settings for the BCM to look for tne humidity sensor are most likely in the Lin configuration since the new harness Taps directly into the Lin of the truck. I haven't had a chance to check yet with the AE tool and see if I can find the settings for it. The total for the new harness,humidity sensor and cover are 110.00 with shipping. The harness simply replaces the old rear view mirror harness. My truck has one pin missing in truck side harness that the new harness plugs into that goes to ignition on run. The rest of the wiring seems to be correct so only one wire will need to be added. That being said Pin #2 in the 8.4 conversion harness is ignition on run so it should be easy to tap into that wire and pin the other end to connect to the truck side plug for the new harness. I'm thinking it would be pretty easy to install the humidity sensor to the upper windshield near the rear view mirror with velcro and would probably look pretty much Factory and most likely work the same. On another note my truck is still throwing the codes for the solar sensor left and right input even though I replaced the sensor. Deer Guy mentioned that sometimes it takes quite a while for the codes to clear so I'm going to keep periodically checking it and see if it goes away. Either way I doubt the sun sensor codes have anything to do with issues we're having with the A/C compressor not shutting off.

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[skuppy069]

That is weird that the solar sensors are still throwing the code .
If you connect with AE and go to the HVAC module and then pull up the solar sensors you can see if they are actually reading anything .
I had some screen shots of mine not reading a couple of posts back .