Blend door issue? (always in defrost mode)

[WestCoastDan]

Seems that we have fallen victim to a failed blend door and/or actuator which now causes all settingsd to shoot out through the defrost vents.
I saw a couple posts when I serched but none seemed to be correct for our '03 and failure mode.
Can anyone point me in the right direction to get started on resolving this?

EDIT- I assumed the failure was blend door related, but youtube video now has me thinking this could be the switch itself.

 

[shortydog33]

I believe that this is normally caused by a vacuum leak in the system, try following the thin black vacuum line that comes through the firewall and into the engine bay in the same location as the A/C lines, follow that around and check for cracks, breakage, or disconnections.

 

[Gollywomper]

Is your blend door vacuum or electronic actuated?

 

[WestCoastDan]

I believe that this is normally caused by a vacuum leak in the system, try following the thin black vacuum line that comes through the firewall and into the engine bay in the same location as the A/C lines, follow that around and check for cracks, breakage, or disconnections.

I started at what i believe is the easiest point to begin diagnosing hte issue and that is at teh T fitting in front of the firewall next to the AC hoses, here:

When I disconnected the fitting where indicated by my finger, there was a significant amount of vacuum present in the line, so I don't think a leak is the issue.

Is there a troubleshooting guide for this system anywhere?

 

[rasband]

When mine had something similar it was a detached tube in top of the transmission tunnel near the accelerator. There's 2 small cylinders there with 4 vacuum lines coming off, mine was one of those vacuum lines being off.

 

[WestCoastDan]

Oddly enough, I removed the dash and control panel, and then removed the vacuum switch, inspected the harness, plug, wires, hoses, and the switch itself for any evidence of the issues shown in several different youtube videos, and all looked good; no melted wires, no melted plastic, no broken clips, etc.

I looked at the vacuum connections at the actuator and manually cycled the arms to the various positions, then I put it back together to watch for actuator movement when I rotated the switch to teh different output positions and it all worked as it supposed to.
It literally must have just been a stuck actuator.

I guess I got lucky.