One of the common problems on many Fords built in the late 90's and 2000's is a leaking EATC unit which causes all of the air to blow out of defroster vents. The fix is quite simple and takes about an hour of labor and a couple of dollars worth of parts.


Parts Required

- 007 o-rings. Quantity of 4. (You can get these from just about any auto parts store. Canadian Tire sells regular viton o-rings. They are 20 cents a piece. If you want something that will last a little longer you can get them in silicone. O-ring dimensions are 5/32 ID X 9/32 OD X 1/16 W)
- dielectric grease


Tools required

- screwdriver set
- socket set


Procedure

To gain access to the EATC screws you will need to remove the dash trim. It is held in place by plastic clip. Easiest way to remove it is from the passenger side. Open the passenger door then grab the edge of the trim and pull. Depending on the year of your car you will have a few connectors in the back which will need to be unplugged.



Undo four 7 mm screws holding EATC unit in place and pull the unit out.



Undo two 10 mm nuts holding the vacuum lines to the EATC unit. Then unplug two electrical connectors.



In order to replace the o-rings you will need to take the EATC unit apart. It's best to do this part inside on a workbench.

Before you take the unit apart I suggest performing a vacuum leak test on the solenoid pack. Attach a hose to the center vacuum port (the port where black vacuum line was connected) and try sucking on it. If you are able to suck any air through the unit, you likely have a crack somewhere in solenoid pack and the o-rings won't fix your problem. You may need to replace the whole solenoid pack or try to find the crack and seal it with epoxy or something similar. If you are not able to suck any air through the hose then you can proceed with o-ring replacement.

In the back of the unit there are two T-20 torx screws. Undo those and remove the solenoid pack.





Disconnect red, electrical connector by pulling straight up on it.



Once the solenoid pack is separated from the EATC control head, flip it over. On the bottom are 10 Phillips screws which need to be removed.





To get to the o-rings you will need to bend metal tabs on each solenoid. Careful not to damage the sponge on the end of each solenoid.





Once the tabs are bent you can pull the solenoids out.

This is what should come out of each solenoid. Notice orientation of the metal valve. It will need to go back in the same direction.



Here is an image showing the o-rings that will need to be replaced. Black o-rings are stock. Orange ones are new. Usually two of the o-rings will be dry rotted and brittle and the other two might seem ok. It is always a good idea to replace all 4 o-rings, especially since they only cost about 20 cents a piece.

Apply some dielectric grease to the new o-rings to help get them into place being careful not to rip them. I used a wooden toothpick to help slide them over the lip.



Once all four o-rings have been replaced reassemble the unit. Assembly is in reverse order of removal.

If you continue having issues check the system for vacuum leaks, broken flaps or regulators inside the HVAC assembly.