About 2 times a year, when I start my truck up the heating and air conditioning unit remains blank. No outside temps show and none of the controls work???

Some times it will come back on after shutting off and restarting... and other times it will not!!!

ABout 3 weeks ago I drove for 40 minutes in 90+ heat and when I stopped for dinner and started back up... it worked just fine and is doing so right now.

Questions.....

1) Is this a fuse issue?

2) Is this a relay issue?

3) Is this a Head-Unit issue (hope not they are expensive out of warrenty)

4) Any particular models or years more prone to this issue?

5) Any recalls or service bulletins out for this?


Thanks....

Jeff

Jeff,

Unfortunately it is number 3 most of the time bad head unit. There have been several replaced under warranty.

and it electronic not enviromental. it is the unit. the new ones are supposed to be fixed.

Sometimes (for some reason) turning the headlamps on and off will help to "wake" the EATC head... but to fix it permanently, it likely needs a new head.

Thanks guys....

How does one know by looking at the headunit if it is a "revised" and fixed unit or not? If my problem gets worse.... I assume I could just go to a junk yard and get a matching one.... but after what model year or "date" were revised ones used?

p.s. - For those of you that work at a dealership.... my birthday is in December and new headunit sent to my home would be greatly appreciated and a great birthday (and Christmas) gift!!!!!


Thanks,

Jeff

Jeff,

I don't know if this will be helpful or not. Had a similar issue on my 06F350.

Took it in for service and it was replaced under warranty. Here is the description printed on the invoice of what was done and or wrong.

"Performed EATC Electronic system diagnosis 19700D. Performed 19700D1 EATC system pinpoint test. found intermittant malfunction. EATC system locks up. Replaced EATC system control assembly 19700D16."

does not list a price for it or anything but that is what was done.

Thanks for the replies....

My truck's EATC head went blank for the first time about two weeks ago. It started working again after I shut the truck off and restarted it again and has been working ever since. I wonder if this is something I should worry about as winter approaches....

Blue Goose said:

My truck's EATC head went blank for the first time about two weeks ago. It started working again after I shut the truck off and restarted it again and has been working ever since. I wonder if this is something I should worry about as winter approaches....

Click to expand...

This is the normal start of the EATC failing completely. This item is covered under the 3/36 warranty, if you are still under warranty take it in and have em change it out.

There is a TSB out on this IIRC

Thank you sir, I kind of figured that one time deal wasn't the end of it...Vince, when is your next work Saturday?

Blue Goose said:

Thank you sir, I kind of figured that one time deal wasn't the end of it...Vince, when is your next work Saturday?

Click to expand...

next saturday! Let me know, so I can make sure the parts are here!

Jeff, If you can get the control unit out, and apart, I would look for cracked solder joints. I have fixed a lot of automotive electronics, that the problem was cracked solder joints.
I even fixed the DME out of a friends Porsche (equivalent to PCM in Fords), that had an intermittent no start / stall problem. I isolated the problem to the 5V power supply (for the digital ICs) which was made up of discrete components, replacing it with a linear 5V regulator. If you look close, you can see the linear 5V regulator, with a couple of wires attached to it in this picture:




Ford also has a problem with the displays going out on a certain model AM/FM CD & tape head unit. The problem is due to bad solder sjoints, which I have taken before and after pictures of here:

Before:






After:








And, just to give you a size perspective, here is the PCB with a penny in front of it: