2003 eatc self-test
BTW the manufacturer is still required to perform safety recalls on your rebuilder.
I disagree totally with your point that the insurance check for a total loss compensates for the loss of warranty. That position is simply giving the mfgr a windfall. I pay for the insurance coverage through my premium. The premium is calculated based upon the expected loss. Why then should the mfgr get to profit from a benefit that I pay for? Ford doesn't pay any part of that insurance premium but still benefits when the ins company pays off by cancelling its warranty. And I pay for the warranty in the first place. So why is it fair that Ford cancels my warranty when I receive an insurance payment based upon a premium that I alone pay? The mfgr deserves nothing in this transaction. If the problem isn't wreck related then the warranty ought to apply.
Took the truck to the dealer. It turns out that it wouldn't go into test mode because there's no trouble codes in it. Whatever is wrong with it doesn't involve something that triggers a code. One of the things they said was that the system was doing what the control head told it to do. So they think the control head is getting bad info.
They believe it's probably the temperature probe. But they also say it could be the blend door actuator, either the motor or the arm or the blend door itself is the way they explained it to me. They ordered a new temp probe and an actuator arm (I think).
I'm to go back in a week. I'll let you know.
Good luck and hopefully your system will be good to go soon.
I've now had the ambient air sensor and the blend door actuator motor changed. Earlier I changed the EATC head. No help at all. The symptoms have not changed. So I've spent $350 without result.
The technician says what's happening is this. First, the unit does go into self-test mode and there are no trouble codes that come up.
Here's how the unit operates. On max a/c or when you set it on automatic and set the temperature on 60 degrees, then the unit works properly. It is full cold and the fan blows max. I can adjust the fan speed manually of course. But the fan speed won't automatically adjust itself. The unit also works properly at 90 degrees, ie full heat and full fan. It's the temp settings between the two extremes where the problems occur.
According to the technician who has watched the blend-door operate, when you run the temperature from max AC or from the auto setting at the lowest temp of 60 up to the next point, 65 degrees, either on max a/c or automatic, the technician says the blend door moves about 50% on this first temp adjustment alone. He says the door moves too much on this first temperature change, he says it ought not to open (or close) that far, it ought to only move a small increment but it moves too far, almost one-half way on the first temp adjustment alone. As you continue to move the temperature up to 70, 71, 72, etc., the door does open only in small increments. It's only on this first adjustment, from 60 to 65, that the door opening is wrong by being too great a movement. Also on the first temp adjustment in either max or auto mode the air quits coming out of the dash and it starts coming from the floor vents only.
If you put it on automatic and 90 degrees and then lower the temp incrimentally, what happens is nothing till you get to about 70 degrees. At this point I can't tell if the temperature is any cooler, but the fan speed does slow down.
The technician is now lost. He says the system seems not to know where it is. It knows at 60 and at 90 degrees, but nowhere in between.
He's not changed the in car temperature sensor nor the sun load sensor. He does say the hose carrying air via vacuum past the in car temp sensor is working but he can't tell about the sensor itself whether it's properly reporting. But there's no error code to indicate something's wrong.
But maybe one or both of these sensors is sending a temperature but maybe it's simply the wrong temp. Under this circumstance then there may not be an error code generated. Is this possible?
Keep in mind the truck had water flood and when we removed the actuator motor there was moisture in the unit and some small amount of deterioration across the position sensing "teeth" but the new unit didn't help at all.
Also keep in mind that the wiring harness under the dash was replaced. Could something not have been plugged in or plugged in wrong that would explain this?
First I have to assume you had the wiring harness replaced with an exact match factory harness for 03 F150 with EATC. I presume so or you wouldnt have been able to connect all the EATC components properly.
So for starters here is the specs for the inside air temperature sensor measured at the two pins of the sensor with connector disconnected. With the vehicle having been flooded there could very well be mud or other corrosion on the sensor which could cause it to read incorrectly
the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F), 37,000-58,000 ohms; 20-30°C (68-86°F), 24,000-37,000 ohms; 30-40°C (86-104°F), 16,000-24,000 ohms
Now the problem with the control head not knowing where the proper position of the blend door could possibly be due to the wrong blend door controller motor. There is most definitely a difference between the controller for manual ac systems and EATC. You MUST use the EATC labeled controller for proper operation. If you inadvertantly install the one for the manual system it will get all whacky.
You also have not mentioned if the outside air temperature sensor (ambient sensor) is installed and operational.
Thats all right off the top of my head I can think of for this situation at the moment. Again you stated previously that the control head was a good one and matched the previous one so I have to assume at this time that it is working properly.
Ford Trucks for Ford Truck Enthusiasts
I think the windshield was also knocked out and some water got behind the dash. So I'm sure there's water there. I already had to replace the light switch and the pedals don't move up and down like they're supposed to. I haven't started working on them yet.
I didn't mention it but he also checked the freon level and it was OK.
My thought on the ambient air sensor is about the same as yours. Since he replaced it and the problems are still there it may have moisture in one of the plugs or the line itself. Maybe some moisture in the sheath. I mentioned that to him and he didn't seem too interested. That could account for the false jump when the temp is moved from 60 to 65. The blend door is moving way too much.
It could also explain why no trouble code. There's a temp being reported, it may be just the wrong temp due to a faulty line or plug.
As far as the under dash harness, the guy I got it from swears it's an exact match. He said the first one he bought from Ford was one digit (or letter) off but they said it would work. He wouldn't install it and made them get him one with the exact same number. He said it plugged up exactly. But one can never tell about a plug that's not in all the way or, again, moisture.
If you have any more thoughts let me know, I'll keep an eye on the posts and let you know what happens next. I'll print out your specs and give them to the tech. I guess next move is to look to that system.
What about the in-car sensor? The one on top of the dash. (I'm right in thinking the ambient air sensor and the in car sensor are two different things, right?) He seemed to want to look at it next.
What about the sun load sensor? Would you change it out too? They're both close to each other on the flat panel on top of the dash and maybe ought to replace them both while he's up there. What do you think?
The ambient air temp sensor is behind the radiator grille usually. When it is properly operating you will get a temp reading on the display that says outside temp. DONT forget to verify the blend door control motor is the EATC model as well.
Here is a pic of the location on my Expy..

And here is the sunload sensor with the auto lamp sensor near it in the top cover panel.

All the book says about the solar sensor is that it must have a resistance between the two pins greater than zero.
Last edited by HomerWinzlow; Jun 17, 2004 at 07:29 PM.
I swear I think he said he thought the inside air sensor and the sunload sensor are together on top of the dash. If so he's confusing one with the autolamp sensor. But it could have been my misunderstanding.
And yes I get a correct outside air temperature.
If you have any more thoughts please post them. I'm going to copy them and take them with me when I go back in a couple of weeks.
Hell, I've got $350 invested, I can't back up now.
Last edited by HomerWinzlow; Jun 17, 2004 at 08:08 PM.
Sorry about the shouting but it's been a long, arduous road, not to mention approx. $500.
I gave the tech HomerWinzlow's suggestions. He wasn't as offended as I'd feared. Sometimes those guys can get touchy but he was fairly receptive. He did check the numbers on the actuator motor for example and it was the right one.
To make a long story short he started going over the connections and found that the control head was not getting any signal from the in-car temp sensor. He told me he got an "open" on the circuit. When he went to the connector,he found nothing obvious but when he cleaned the pins and the female plug with electronic cleaner and replugged it, the thing worked. It works perfectly as a matter of fact.
The strange thing, according to him, was that even though the control head wasn't getting a signal from the sensor, it didn't generate an error code in the system.
In any case Im happy to hear it is finally working for you. Thanks for the update.
You may be right. Perhaps there was some signal but not enough to register on his meter. But one of the things that became apparent to the tech after he found the source of the problem was that all along the control head has not known what the temperature was inside the vehicle. He says that's indicated by the fact that the EATC worked properly only at max low and max high adjustments and nowhere inbetween.
He first thought that the blend door actuator was moving the door a certain distance on the first adjustment from 60 degrees to 65 degrees. But on further observation this first move was not a "certain distance" but was in fact a random distance. Thus it was clear that the head had no info as to temp and when asked to reach a "certain" temp, ie a temp other than max high or max low, it didn't know what to do and moved the blend door randomly. Sometimes a little and sometimes a lot.
To me this indicates that even if there was "some" signal from the temp sensor it was a signal less than that necessary to inform the control head as to the interior vehicle temperature. You would think if this were the case, that Ford would set the control head to generate an error code when it failed to get enough of a signal from the temp probe to be meaningful to it.
But, of course, that's in a perfect world. And you could be correct that some, but not enough, signal might not trigger an error code while at the same time not informing the control head.
I guess the moral of this story is that you can't just depend on the EATC's error reporting mechanism. That's the first thing the tech said to me after he found and fixed the problem was that he was surprised the different parts of the system weren't connected any better than they were. "Why have an error code system if it isn't going to find an error like this one?" It really only makes the job harder because you are fooled into ignoring the real cause of the problem. He thought all along that the head was getting a temp, just the wrong one. Then after he replaced the probe, he thought that even though it was getting a temp and was getting a correct temp, the actuator motor was behaving incorrectly by moving the door too much and so he replaced the actuator motor. But all along the head was getting no temp at all.
With 20/20 hindsite that's the mistake here that cost me $500, not looking for the obvious. But with a flooded vehicle I guess you'll run into these problems.
Last edited by ausbeer62; Jul 1, 2004 at 10:18 PM.






