I own a 2004 Trailblazer LT EXT. Until recently (that I noticed) my rear a/c was working fine. Now the blower doesn't work properly. In properly I mean that it does turn on and work when the engine is OFF and the ignition is on. If the engine is running it wont turn on. I set the controller to allow the rear passengers to control it and it still won't work. I do feel a small amount of cool air coming from the lower vents when it's on. I turn the fan off and attempt to put the a/c on high and I hear the rear blower briefly attempt to start and then quickly turn off. Does anyone know what the problem can be and how to fix it? Any help would be greatly appreciated.