Rear Blower Headaches

[jusbigp]

Hello GMT Nation
This is my first post so bare with me. My problem is that my rear blower will not work when the engine is running.
If I put ignition in run position fan will run until I move control or start engine.Does not matter from front or rear controls.
Had been reading around this site and the other site with few threads that came close, but saw some fixes other people had tried.
pulled fuse at rear fan would run 5 to 10 seconds than stop.I read a thread where a guy had a very similar problem. He said that the rear
HVAC control module was bad]could this be my situation or something else. btw I have 2004 trailblazer-ext 2wd
with manual controls
View attachment 8055

 

[Mooseman]

Definitely a strange problem. At first glance, I might have suspected the ignition switch where it is often blamed for electrical weirdness. Are there any other systems affected in any way? If everything else is working OK, then that controller might be suspect but at $108, it's an expensive trial and error.

Personally, I have never used the rear HVAC since it has never worked since I've had it.