Arduino Based EATC Replacement

The Electronic Automatic Temperature Control Module on [Dan Mattox’s] 2000 Ford Taurus bit the dust. The junkyards in the area didn’t have a matching replacement and a new one is pretty hard to come by so he built an EATC  replacement from an Arduino Mega. It includes a solenoid controller board for the vent selector, blower control, and new switches to control the power windows. He’s got the system up and running which is important because after removing the broken EATC the car was stuck blowing 90-degree air at full blast. He’s put together a demo and an installation video which we’ve embedded after the break but there’s also a photo album you can page through. The sketch that we developed to control the system is up at pastebin so get it while it’s hot.





27 thoughts on “Arduino Based EATC Replacement

  1. Nice that someone took the time to solve a problem like this, its just too bad they applied so much effort to a problem that didn’t need to be solved.
    Those things are available for $25 from almost anywhere, including junkyards selling on ebay if you are too lazy to even check out the local yard.

    What a waste. That energy and skill could have been applied to something, you know, not irrelevant and redundant.

  2. I would have reused the old dash controls with the new board vs make new controls.

    Though before considering the EATC board dead I would have attempted to repair it checking for cold solder joints and bad caps.

  3. I cannot believe some of you are bashing his efforts. Yes, it might be an ugly looking project but it works. And it is much more difficult and creative than a dude making a nonsense wrist watch with arduino. Somehow you eat up the arduino wrist watch but this project is bad, what gives?

    Is it an overkill? Maybe, at lease he has the knowledge and persistence to finish a project.

    I don’t think he deserves these personal attacks.

    Good job Dan!

  4. Yea I would have tried to tie it into the original controls, but whatever, its not my car

    project box is ugly? so what, its a standard issue radio shack model (which is nibbler would stop being a retard for a second and actually did something that took more skill than spouting off on a wordpress site he would know that)

  5. Umm yeah, I just checked inventory, and hundreds of junkyards all over the country have the replacement part available to be shipped. A majority of them are asking from $20-$40 for the part.

    It’s cool that he wanted to spend the time doing this, but it’s prudent to point out that it’s a complete waste of time. There are sooooo many taurus/sables in junkyards, to think that a part like this is not available is crazy talk. This guy obviously only checked his local junkyards.

    Next time, use – That’s your junkyard search engine for North America. For the module he needed, select Computer Box – Not Engine, and then select “Temperature Control”.

    That being said, the failure in his original module was probably a really easy fix. I repair dash clusters, PCM’s, and other control modules on a weekly basis. They are rarely unrepairable, unless its related to a MCU die failure, in which case, I send the customer to

    Not trying to bash his efforts, but damn, this could have been fixed for under 30 bucks.

  6. Oh, and by the way, if he actually needed the control that mounts on the dash as part of the radio (instead of the control unit), then you select Radio/CD on, and then select “AM-FM cass-CD cont, auto temp”. Once again, could have been had for about 30 bucks.


  7. @ Dan Mattox: Good job!

    For all you negative people out there: Pbpbpbpb! I would love for Dan to take a look at the heater/AC controls in my S10 Blazer. My stinking mechanics don’t seem to understand that I want it fixed, not switched from defrost to vent according to the season. Those are some idiots.

  8. Since when has hacking been overly concerned with doing something the most economical way? Dan actually DID something and acquired some knowledge along the way – and he probably had some fun at the same time. Go Dan!

  9. All this bunch of cables and electronics just to control the stupid fans huh?

    “The junkyards in the area didn’t have a matching replacement”
    Ever heard of Ebay?

    TBH that’s why I love company cars, you can even intentionally break them then your company takes care of the repair or gives u a new one :D

  10. Did anyone look at his pics? Everyone is out of focus.

    And yah he probably spent $100 to build something he ciould have got for $30. In economic times like these that is a no no.

    Now if it had a blinky LED on that arduino, then we could all agree it was worth while.

    p.s. nice build ;)

  11. I just started working at a company that rebuilds industrial controls.
    It seems like you could almost make a post out of doing exactly what was suggested earlier, namely taking a multimeter the old mark I eyeball and attempting to find out what failed on the original control board and repairing it.

    Not that the project is that bad. They are keeping an old car running one way or the other.

    I know I’ve been there (I think many of us have), but my old ’79 Cougar only needed a block of wood to prop up the heater fan and an on/off toggle switch to be hacked. ;)

  12. Door lock control board in my ’94 Accord failed. Not as critical as the heater being wedged on full, but annoying nonetheless. Replacement part is about $75 at junkers, wasn’t available at my Honda dealer at all.

    Cracked open the welded plastic module casing. Tested based on service manual and tracked the fault to a bad solder joint on a relay that I hadn’t noticed from visual inspection. Reflowed all joints on the simple board, glued the case back together. Works great now. Total time for repair was like an hour, including disassembling the driver’s door paneling to get at the module.

  13. Ok. The part that went is the Integrated Control Panel. It is not on EBAY for EATC cars, thats the automatic thermal controls, buttons not knobs. Ford knows the equipment is crap and discontinued it shortly after my car was made. NONE of the junkyards in my state have the panel. NONE of the parts sites I HAVE searched have the panel. The panels requests are routed through a “rear control panel” which I could have gotten for $45. After all the work, I learned of an option to switch to Manual controls for about $90. I realize my fiberglass panel replacement is ugly, I’m an engineer not an artist. Read up on the Eatc, you arent just interfacing fans… Thanks for the people who appreciate it, I will add a blinking light later…

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