How to: Add Dual Zone ATC to a Tradesman

[crash68]

I set the temp I want and the a/c compressor turns on/off as needed to go down to the temp set, if I hit the a/c button it shuts off the auto setting

If you hit a button for the HVAC system while in Auto mode it usually knock it out of Auto.
The temperature set point still works whether it's in Auto or a manual mode.
Full Auto controls the fan speed, mode door position, recirculation door and AC operation.

 

[2016 2500]

If you hit a button for the HVAC system while in Auto mode it usually knock it out of Auto.
The temperature set point still works whether it's in Auto or a manual mode.
Full Auto controls the fan speed, mode door position, recirculation door and AC operation.

ok, so it is working exactly as it should be.

 

[Mpgrimm2]

ok, so it is working exactly as it should be.

Correct. Thanks @crash68 !

 

[Mpgrimm2]

did you ever figure this out i did the same and have the same problem im using grimm's harness to add the 2 temp sensors in do i still need to repin the harness if this box was a dual zone to start with complete with wiring harness from the same year truck?

Shawn,
You have all the correct wiring with the harness setup I sent you for either Single Zone ATC or Dual Zone ATC...
Keep in mind however that you have a very non standard 5th Gen UAx 12" radio screen grafted into your 4th Gen truck with the 4th Gen HVAC controls ...as far as I know you and @SitKneelBend are the only 2 with this experimental setup.
.

 

[SitKneelBend]

Shawn,
You have all the correct wiring with the harness setup I sent you for either Single Zone ATC or Dual Zone ATC...
Keep in mind however that you have a very non standard 5th Gen UAx 12" radio screen grafted into your 4th Gen truck with the 4th Gen HVAC controls ...as far as I know you and @SitKneelBend are the only 2 with this experimental setup.
.

He also implanted the dual zone setup in his truck and maybe a bunch of other stuff. I'd say my setup "was" experimental, but @reyokonova was going for "bleeding edge"!

 

[reyokonova]

Shawn,
You have all the correct wiring with the harness setup I sent you for either Single Zone ATC or Dual Zone ATC...
Keep in mind however that you have a very non standard 5th Gen UAx 12" radio screen grafted into your 4th Gen truck with the 4th Gen HVAC controls ...as far as I know you and @SitKneelBend are the only 2 with this experimental setup.
.

i dont think the screen is a issue since even comanding that blend door to move from alfa obd it does not move

 

[reyokonova]

He also implanted the dual zone setup in his truck and maybe a bunch of other stuff. I'd say my setup "was" experimental, but @reyokonova was going for "bleeding edge"!

yes i installed a dual zone box from the same year truck with complete harness on the hvac box and the blend motor is not moving for the pasenger side even when being told to do so from alfa obd it also fails to run the calibration as well. maybe it has a bad motor from the junkyard?

 

[reyokonova]

any one have any advice here i just got my truck back from the body shop after 2 months and these cold mornings really suck with no heat

 

[reyokonova]

Here’s a refresher so all the details are in one place.


My truck originally started as a single-zone A/C Outdoorsman EcoDiesel. After doing Grimm’s upgrade to single-zone automatic A/C, I initially had no heat. That turned out to be a bad diverter valve. Once that was replaced, both heat and A/C worked correctly.


Later, the evaporator core sprang a leak. Since I had to pull the dash anyway, I decided to go ahead and do a dual-zone HVAC box swap. I sourced a complete dual-zone box from a junkyard, including the full wiring harness, from the same model year EcoDiesel. Before installing it, I verified that the heater core flowed freely and flushed it as well.


After installing the dual-zone box, I once again had no heat.


Further diagnosis showed the truck had a thermostat stuck open, which has now been fixed. The engine now holds steady around 192°F instead of ~150°F. I’ve verified that I have hot coolant entering and exiting the heater core.


I’ve manually actuated all the blend doors using AlfaOBD, but the passenger-side blend door test never runs. I’ve also noticed that with the A/C button off and the system calling for full heat, the A/C compressor is still cycling on and off. It’s not running constantly, but it behaves as if the system is in cooling mode. That seems odd, since airflow must pass through the evaporator before reaching the heater core, meaning the system may be trying to heat already cooled air.


My next step may be to tap into the two wires for the passenger-side blend door motor and temporarily connect a motor from my old HVAC box. If it actuates, that would point to a bad blend door motor. If it does not, then there’s likely another underlying control or wiring issue.

 

[reyokonova]

Final update for anyone else who goes down this road: SOLVED


The issue turned out to be with @Mpgrimm2 harness. The one cable he left out, wait for it… was the wire for the passenger-side blend door .


I bypassed his harness, and everything functions exactly as it should through AlfaOBD. I now have nice, toasty heat and ice-cold AC.


That said, I don’t recommend running it this way. As @SitKneelBend pointed out, without the temperature and humidity sensors, the AC compressor runs nonstop.


The proper fix is to add the missing connection on pin 3 of his connector, and you’re good to go. Hopefully future versions of the harness will include this wire, or maybe even a true dual-zone version… though there probably aren’t that many of us crazy enough to attempt the full, true dual-zone upgrade

https://www.digikey.com/

 

[Mpgrimm2]

Final update for anyone else who goes down this road: SOLVED


The issue turned out to be with @Mpgrimm2 harness. The one cable he left out, wait for it… was the wire for the passenger-side blend door .


I bypassed his harness, and everything functions exactly as it should through AlfaOBD. I now have nice, toasty heat and ice-cold AC.


That said, I don’t recommend running it this way. As @SitKneelBend pointed out, without the temperature and humidity sensors, the AC compressor runs nonstop.


The proper fix is to add the missing connection on pin 3 of his connector, and you’re good to go. Hopefully future versions of the harness will include this wire, or maybe even a true dual-zone version… though there probably aren’t that many of us crazy enough to attempt the full, true dual-zone upgrade



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https://www.digikey.com/

Dual Zone blend door wiring is available as a listed option when ordering the ATC add on harness set.
9.9 of 10 people don't want it or have any interest to pull the dash, refrigerant, & replace the plenum box, etc for dual zone ATC. (You just have to ask to have it added during the build).

.