I have a nice 2003 Ex Limited with 6.8 and 4 X 4 that has a blend door problem . has anyone done the Dorman style repair ? Cutting into the heater core housing .
Their picture is not clear as to where to make the cuts .
Thanks for the help.

 

This may or not apply, but I just had a similar issue with my 2001 7.3 Excursion.

Not sure if my problem was the blend door or the Max door. My mechanic fixed it, not me.

I know you have a gasser, so the vacuum systems are different, since diesels do not make vacuum. (Diesels use a small fish tank like compressor) But your system still uses the vacuum that the gasser makes naturally.

I also had the same issue over 10 years ago, and the fix was the same.
The reason 2 different mechanics, 10 years apart, had the same problem finding the issue, is that the Excursion systems are slightly different than the F250/350 trucks.

Both the mechanics were highly experienced Ford Master techs. The 2nd mechanic found the issue differently. The first mechanic started looking at the rubber lines in the dash by the ac switch. And started tracing the vacuum lines from there. Took a while to figure out. On the most recent repair, the mechanic started looking at the lines in the engine compartment. Turns out the 2nd mechanic found the problem in a few minutes, instead of a few hours.

First, he removed a plastic cover under the glove box. And looked at the doors to determine if they were functioning properly or jammed. Then he started looking for the leak in the engine bay, after he found the doors functional.

The issue was not that the door(s) were broken, but that they were not getting the vacuum pressure.

Check this out before you do anything more difficult and expensive!

The symptom I had was that I could not get max air. Only recirculate. And air out of the defroster on max position. And only a modest volume of air coming out of vents. Found a broken rubber vacuum line and the issue was fixed.

Hope this helps someone with an Excursion.

 

What exactly is the problem you are having?
Since you are a 2003, you most likely have the digital dash climate controls? if so you probably have the electronic blend door actuator?

 

In my case,
an '02 Excursion

the blend door is not moving at all.

I started under the hood tracing Vacuum lines.

bought a new OEM Vacuum harness line set that goes from the Vacuum Pump to the Canister, and Tees off for other stuff also.

Still had no vacuum, I isolated all the lines under the hood, still no vacuum.

one line left, it goes thru the Firewall to activate the HVAC controls.

a MityVac proved that is the culprit....
something is broken under the dash, gotta get it opened up and find what is wrong.

 

Are you only getting air thru your defroster ? Have you checked the 4x4 vacuum switch located on the inner fender just behind the battery, common problem on our Ex’s, The switch cracks and causes the air to only flow thru the defroster however it will alternate between the vents and defroster. $50 part on Rockauto and an easy fix

 

Confused with what is not working ... the Blend Door (electric actuator) or the Recirculate/Max AC door (vacuum actuator). Sounds from your description it is the latter but you call it the Blend Door. The vacuum lines for that one are way back on the firewall inside the glove compartment. In my Ex that vacuum line is yellow (while others are gray) and very hard to get to without taking a lot of stuff out of the way. From inside the hood, if you remove the blower fan, you can see the door but not the actuator. That is the extent of my experience checking that it was working.