Hello, new to the forum and thanks for the add! I have a 1996 K1500 that will not switch from floor mode to defrost (or any other mode that I can tell). I'm leaning towards the mode door actuator, but I've heard of the door itself possibly having issues or even control heads failing. Just curious if anyone'* ran into this and knows of a quality test. Thanks in advance!

There are only three wires to the actuator.....power, ground, and the signal wire that can be checked with a voltmeter......you can remove the actuator, and manually move the door to see if it is free...

Thank you, will give it a try!

Looks it is an actuator issue. Found a great deal for it (almost 40% off) and other OEM parts @ gmpartworld.com!