Have searched thru the site and found threads about the EATC orings going bad and air blows only thru the defrost, but not much on my problem. My EATC will power on as normal (entire display lights up, then switches to operating mode) then after a minute or two will go blank. Then display lights up again and comes on again where it was before. Lately, it will just flash several times on startup, blank out for a few minutes, then finally come on. Seems that once it warms up, it operates fine, but getting progressively worse. Very random....but seems to remember the last setting it was in once it finally grabs. I changed the 10A fuse to be sure that was not the source of the intermittent problem....it was not. Thinking the EATC is the issue, but want to be sure before i buy a new one....they are pricey.

Is there a way to diagnose the EATC? I read something about unplugging the EATC for a few minutes and reconnecting it to reset. I've tried this with no luck. Any suggestions? Anyone ever seen this problem?

Thanks in advance for any help.

 

Check your charging system first. Low supply voltage will cause the EATC to do weird stuff.

Yes, your EATC has a built-in self-test, but it's unlikely to identify what's wrong based on your symptoms.

 

Problem Solved: Turns out it was a bad EATC unit. The intermittent display blinking got progressively worse. Must have been a bad solder connection on one of the circuit boards. Found a remanufactured EATC on ebay for $100 and swapped it out....so far, so good....no more intermittent display problems.

A few items to note: when first installed and powered on, it was displaying degrees C. After a brief search, I found a post that described how to change it. With the unit powered off and outside temp displayed, hold the two outer control buttons down for about 2 secs. (on mine, these were the Max A/C and the Defrost buttons). This changes the display to degrees F. Repeat and it will change back to degrees C. Found nothing on this in my 2003 F150 owners manual, so was glad to find it on these forums.

Lastly, if you replace your EATC, make sure that the part numbers match exactly. I noticed that the shop that rebuilt this new unit had scratched off the original part number and placed a sticker on it that matched my part number (2L3H-19C933-AA) Though it functions the same and the faceplate and all the control buttons match, the mounting holes were different and I had to rework the mounting flange to make it fit my truck. This wasn't a big deal, but since the seller sold it to me by exact part number, I should have been able to expect it to be a perfect match. I guess that's what I get for shopping on ebay, but the price was right. Most remans I found (amazon, rock auto, etc.) were priced $250-$500.

 

Did you have to send yours back as a core?

If not I wouldn't mind taking a peek at it and see if I can find an easy repair for it.

 

Sorry, yes had to return it to get my $125 core charge refund.

 

No problem. Figured I'd ask.