I had asked if anyone had taken a control head apart to see if it was fixable and got no answers. So, being the skeptic, I opted to do it.
I had vacuum problems in the control head, where the ac defaults to the defroster. There are some o'rings that need to be replaced to solve this. Total cost was about an hour and a half of my time and $2.95 worth of o'rings. It now functions just like it is supposed to, and I saved about $500.00 bucks.

I do not have time right at this moment to write it all up, but I will later tonight if anyone is interested in doing their own.

Thanks to all here,
devilsrighthand, aka Mike

 

I'd love to hear about how to fix this! I've been looking for a used unit, but have yet to find one. I'd appreciate any information you can pass on. Thanks
-b.

 

OK, this will not fix a blend door problem or a vacuum leak anywhere except in the control head of the EATC unit. So, if you have done all the tests, and are sure it is the control head that is leaking, this will save you a few hundred dollars. I am going to assume you know how to remove and install the control head, so we will start with the unit on a clean and workable surface. I did not take pictures as when I did this, it was strictly exploratory surgery. I wish I had of.

You will need, 4 new o'rings, 9/32 O.D. I found these at my local ACE Hardware store. A pair of needle nose pliers, a small straight blade screwdriver and small phillips screwdriver, a T-20 torx head driver and maybe a medium flat blade screwdriver.

With the unit out and laying on your work surface, look at the back side and you will see 2, T-20 torx head screws, remove these. Now you can lift up on the back of the unit and remove the bottom, lift the back up and pull towards you, there are 2 tabs at the front that will slide out of there respective slots.
When you get the bottom off, you will see the wire that runs from the vacuum actuators to the circuit board, unplug this from the circuit board and set the top half of the control head aside. Turn the bottom over so you can see the 10 phillips head screws, and remove all 10. Also set aside the strap that holds down the vacuum manifold.
Now lift the vacuum manifold and the actuators off the bottom of the unit, it will all lift in one piece. The black plastic unit down the middle is the vacuum manifold and there are 2 actuators on each side. Hold it so you are looking at the ends of 2 actuators away from the manifold. You will see what is a piece of foam type material with 2 metal tabs bent over, take a pair of needle nose pliers and straighten these out. Now you want to wiggle this end piece with the foam out of the actuator, I had to use a small screwdriver to GENTLY pry this end piece up and out of the actuator. It is about an inch long, and on the end that fits inside you will find the little o'ring that needs changed. DO NOT TURN THE MANIFOLD OVER, THERE IS A SPRING AND PLUNGER IN THERE DON"T LOSE THEM. Take the old o'ring off and replace with a new one. I sprayed a little silicone on my fingers and wiped around the new o'ring to help seat it back in. DO NOT USE PETROLEUM BASED GREASE OR OILS TO LUBRICATE THE O"RINGS. You want this clean and no oil on it when back in.

With the new o'ring installed, insert this back into the actuator and push down until o'ring is inserted back into the chamber, it will be a tight fit. I got them in as far as I could with my fingers, then used the handle of a small screwdriver to finish seating it. Rebend the tabs over like they were and you are finished with that one. I recommend doing all 4 actuators as I found one o'ring brittle and the obvious one leaking, it came out easier than the others.
If you do them all, it may save you some problems down the road.

If you have trouble getting the new o'rings to seat all the way, just take your time, they will work, just keep using gentle pressure and all will seat. When you are finished with all 4, mount the assembly back on the control head bottom with the 10 phillips screws and don't forget to plug the wire back on
the circuit board.
Install back in the dash and check all functions to ensure they all work before buttoning up. Sit back and enjoy that blast of cold air from the vents,and be proud, you just saved a bundle of money.

I have tried to explain this as best I can, if you have any questions, feel free to ask. It really is a simple fix, takes about an hour and a half and that includes removing and reinstalling the unit in the dash for me.
Above all, take your time and do not break anything, I have no idea where parts would be available.

devilsrighthand, aka Mike

 

Thanks a lot for the how-to...I'll tackle this project this weekend!
-b

 

Hope it works out for you. It really is easy to do.

 

Great rebuild job
It only needs some pictures

 

Excellent rebuild guide. Do you know what the ID of the 9/32" o-rings was, or what the x-section thickness was? Usually o-rings are identified by a 2-xxx number. If not, I'll see if I can post the size when I tackle this.

Thanks for the write-up. Saving money is fun!

 

No, I did not notice the inside diameter. Like I said when I did this it was strictly, exploratory surgery. I just grabbed up o'rings that were close in size to what was on there, and they were marked 9/32 O.D. they were a little thicker than the originals. But, they work just fine. I would suspect that the originals are probably a metric size.
I hope this works for everybody, it seems a shame to have to spend hundreds of dollars just because some o'rings get old and shrink or crack.

I hope everyone will keep me informed as to whether this works for them.

devilsrighthand aka Mike

 

Yes you can rebuild several items within the EATC, but in reality I haven't seen many that really needed it.
I did almost exactly what you did for a friends Navi a while ago. He had damage that was mechanical in nature involving the SMT push-buttons, and lights. An exact replacement was somewhat out of the question for my friend (financial problems). Based on a loss-loss situation I decided to remove the EATC to see what was "fixable" inside.
Several of the "O" rings were available in my boxes of rings from air conditioning kits, and even the Home Depot.
Several were refurbished as is using silicone grease from a tune up kit to resurface existing rings and assemblies.
As it was I did fix his EATC including the actual cause of his problems (crimped vacuum lines, plug connections).
The basic problem lies in little available information directly concerning the EATC, Manufacturer preference for replacement option as service. There are Rotunda Service Jigs for diagnostic work, but they are usually unavailable or too expensive for home mechanic service work.
Probably the least expensive method for diagnostic work on a EATC problem would be a unit substitution check.
Good luck on your rebuild.

 

Tried your fix and it seems to be working so far no defaulting to defrost thanks for putting on here had this problem for a couple months, straight forward just like you wrote it anyone with a little know how should be able to do it took about hour and a half. I used 9/32 o.d. By 5/32 id orings and worked fine i had one that was broke and another pretty brittle and two were fine again thanks for the help

 

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Dude, You rock. Thank you for posting this fix on here, I have been dealing with this for the last couple of years however this year has been the worse.

The only way I could get any air through my vents were to run it on Panel-floor.

This morning I pulled the unit out and began to pull it apart just as your instructions say to do so. I come across the small o-ring but was thinking for some reason or other you were talking about another one down inside the hole. Turns out I was trying to make an easy job into a harder one. It didn't however take me long to figure out that those were the ones that you were talking about. I pulled off three of them that actually broke off in my hands.

I hooked it all up before re-installing anything to be sure that everything was going to work correctly, started my truck, hit the Max button and what do you know, Cold A/C coming from the vents just as it should.

Thanks again for posting this fix and for you guys about to tackle this job, just follow the directions, its that simple.

 

I too have this problem. All air is blown through Defrost regardless of what mode is enabled. This problem was only temporarily switching from floor/dash (blew heat through vent/floor for about 30 seconds then switched to Defrost) but has gotten worse now is stuck in Defrost. HOW DO I REMOVE THE CONTROL HEAD ASSEMBLY WITHOUT REMOVING THE DASH. This is for the 2003 Ford F150 Harley Davidson, Crew Cab.

 

The radio bezel just clips on.
Grab it with your fingernails to prevent scratching the dash and pull working your way all the way around.
after you have removed the bezel you will need to remove the four t20 torx head screws.
I have an aftermarket radio that had to be taken out prior to the EATC being removed, you may or may not have to do this but it sure makes it easier.
Gently pull the EATC out and up to clear the lower part of the dash.
Remove the 2 nuts that hold the vacuum lines and carefully remove the rubber manifold from the unit.
Unplug the 2 plugs and your out.
Total time to remove unit from the truck takes about 15 minutes.

 

THANK GOD I FOUND THIS THREAD!

Major props to you devilsrighthand!

Don't have time to read through it all but pics would be great if you can.

I'll sift through it but just yesterday my vent would be the only option to blow air out of the normal vents and anytime i switch to anything else (max a/c, auto, panel/floor, floor, def) it would automatically switch over to the windshield vent and that's it!

Sometimes if i go from "vent" to auto it will work for about 30sec and then you can hear that it seems like you said some sort of vac problem and BAM it reverts back to the windshield vent.

Luckily the AC still blows cold but this sux!

Edit: How do i know i don't have a "blend door" problem? Is there a protocol to follow for diagnosing?

From the other posts it's sounds like we all have the same problem to a certain degree.....i guess mine is in the intermittent stage......boo.