If you have manual HVAC and are wanting to convert it to auto I have collected a set of wiring diagrams and played with a junk yard F150 with the system to figure it out. The project cost me only $100 but that will vary depending on where you attain your parts. This junk yard gave me a VERY good deal being that is what just the EATC cost at some places. There are some aspects of the system that I am still trying to figure out, however I will update as I figure them out. I will post connector views so you now which pins to mess with but no wiring diagrams out of respect for my source because they do own the images and the wiring diagrams aren’t needed with this guide and will just make things more confusing.



A list of parts that you’ll need:

EATC: 4L3H-18D422-CG

Blower Motor Controller: 4L3Z-19E624-AA

Cabin Temp Sensor: 18750-05346198

Center Trim: This will be different based on if you have console or column shift. I cant find a definitive part number but they are easy to find. Just make sure the area where the controls go are a smooth oval and does not have the bumps that would match the manual system.

Gauge Cluster Surround Trim: Again the part is going to be different based on the color or your dash. Just ensure it has the vent holes on the bottom right part of the trim. This is where your air temp sensor is.

Temp Sensor Tube: There is a tube that runs from that temp sensor down to the ducting. I’m not entirely sure what it does. My guess is it draws air towards the sensor. I cant find it at all online so it’ll have to be a junk yard find.

**Steering Wheel Controls: 6L3Z-9C888-AB

**Clock Spring: 8L3Z-14A6664-A

Wiring: This is where you have to get creative. You can replace the whole dash wiring but that requires a lot of disassembly. While that will be the most OE way of doing that it can get expensive and cause damage if you aren’t careful. This is where wiring diagrams come into play. The least expensive way to do this is to get the connectors for the Motor controller, the second one for the EATC ( will go into that later), and the temp sensor. I’m not sure how an FX4 or XL/T, STX gauge cluster will react with this system because I’m using one out of a king ranch/lariat. I’m not sure if that is a component that needs to be swapped as well. I was able to pick up one for $100 and it is fairly plug and play besides losing AC. (More on that later)

12 Gauge Butt connectors

18-22 Gauge Butt connectors

T-Taps

A roll of 18 gauge wire

A foot or so of 12 Gauge (black) wire

12 gauge ring terminal

Brown pin/wire from the sunlight sensor

** = Optional

Things I dont have worked out yet:

-AC control: I have not gotten that far on this part yet, but I suspect the EATC module will communicate with the PCM via the UBP communication wire. You also will most likely need to have your ECM flashed with the EATC settings in order for it to know that’s where the AC signal will come from.

-Heated Seats: Some EATC modules come with heated seats. I didn’t hook up the system ( because I dont have them). I believe they will connect to a seat module, which that module will give you a number of extra features.

-Heated Mirror Control: I believe this will run through the seat module but may run through the UBP as well.

-This system uses UBP communication to talk to the other modules and the DLC. I however do not have it hooked up yet. So i am unsure of how well the rest of the truck will like it being that its not programmed for auto HVAC. However I do suspect that this can be remedied with ECM flashing either at the dealer or with an VCM 2.


Things to note:

-I suggest pulling this stuff off a parts or junk yard truck other wise it could get VERY pricey.

-Steering Wheel controls are not required.

-Heated Seats are not required.

-The larger plug EMTC (C294A , which now will be C228A) does not need to be modified and will plug directly into the new unit.

-Cutting into the ducting system will need to be done unless you are gonna replace your assembly with a auto HVAC one. It’s not major or hard to get to but this is to ensure the controller gets air flow and doesn’t overheat.

-I will refer to the connectors by the name for has given them which is what’s listed on the top left of the connector diagram. The only existing connector that you will need to modify is the sunload sensor (if your truck already has it)

-Options on my F150 may change your installation slightly based on your trim level and options. My truck is an XLT with the sunload sensor and has a swapped in King Ranch cluster.

-When I mention EATC I am referring to the module that does the work (contains the controls, screen, and operates the system)






1)

You’ll want to start with your wiring. Well start from the drivers side. Remove your gauge cluster surround, kick panel, and defrost trim, You’ll also want to remove the center console trim and remove the old EMTC and trim. You’ll need to insert that BROWN wire/pin into C286 for the sun sensor into pin cavity 1. Run that wire from C286 to the BROWN wire coming from C228B for the EATC unit.

2)

You then will want to wire in the temperature sensor. This is also going to wire into C228B. Connect the PINK/BLACK wire from the cabin temp connector to the same colored wire on C228B and the WHITE/ORANGE wire to the same colored wire on C228B.

At this point you’ll also need to route the “air guide” tube from the vent down to the ducting. This area is accessed by removing the black cover in the bottom center of your dash. You’ll see the circular inlet that it connects to. At this point you are done on the drivers side. We now need to move over to the passenger side and remove the glove box and the dash trim panel in front.

3)

From here we are going to work on the controller plug C271. Now you’ll need to cut the old blower motor resister connector off. Leave your self plenty of wire to work with but I suggest leaving a little bit with the connector to reverse it back to manual if need be. The DARK BLUE/WHITE and YELLOW/RED wires are not needed so you can cap tuck them away if you’d like. Take that 12 Gauge BLACK wire and ring and connect that to the BLACK wire coming from the plug. You can ground that with the screw holding the glove box latch.

The BROWN/WHITE wire coming from C271 will connect to the BROWN/WHITE wire you cut going to the blower motor connector. The BROWN/YELLOW wire coming from your new connector will T-TAP into the BROWN/YELLOW wire coming from the blower motor plug.

You will then need to wire the LIGHT BLUE/ORANGE wire coming from your new plug into the LIGHT BLUE/ORANGE wire coming from C228B for the EATC module.

Connect the VIOLET wire from C228B to the VIOLET wire going to the DLC (OBDII Connector)

Now test everything to make sure it works properly and dont let the controllers cooling fins touch metal or it’ll ground out and only blow on high.

This is as far as I went for wiring, this gets you a basic EATC system. Steering wheel controls shouldn’t be hard, but I dont have enough info to write a step by step for it. Heated seats I believe have their own module that you’ll also need if you want that feature, same goes for info on those.

4)

Now for the cutting I promised. Take a measurement of the cooling fins of the controller and measure them. Then add about 1/16 of an inch to each side of your cut. (You dont have to do it that way it’ll just be cleaner. You can just cut and fit too) you’ll want to cut out the area where the old resistor was and then cut to your measurement so that you can insert your controller so that it can be cooled. Once in secure with a self tapping screw, I also suggest going around it with RTV lightly to seal it and secure it better.

Put everything back together, and now you should have a semi operational EATC system.

*Disclaimer
I do not suggest beginning conversion at the moment until I have the AC issue ironed out unless you have a good idea on how your trucks communications protocols operate or don’t need/want AC. However I do not take responsibility for any damage that occurs and I do suggest that whomever may perform this be ASE electrical systems certified. I did try to make it as simple as possible for those who with to attempt this with out prior knowledge.

 

Just to clarify - All of that just so you don't have to adjust the temp and fan settings as you need?

 

To be fair... yes. However I wanted my truck to regulate a certain temperature with my remote start so I didn’t have to adjust it before leaving it.

 

Gotcha. Good luck!

 

Something to think about, the interface/control is NLA, so if it breaks, you're gonna go dumpster diving again for parts.

Good luck!

 

Did you ever finish this? I have everything needed but would like to know what your issue was and how you resolved it before proceeding. Thank you!

 

To add to previous post, donor is a ‘07 Lariat, mine is an ‘05 FX4

 

Don’t see point of this. Manual setup is more reliable and cheaper to fix (if you ever had to).

 

Personal preference. And don’t want to buy a new truck

 

Well, you kinda have to.

Otherwise, just scoop a whole Lariat or higher trim dash out along with everything behind it and go to town. Even the gauge cluster figures into the EATC setup and I don’t see mention of that being acquired by the OP.