'00 HVAC actuator questions

[Number21]

I recently bought a 2000 Silverado 1500. The heat/AC is stuck in middle vent option, no defrost. Other than this it seems to work fine, and I've read about the actuator that probably needs to be replaced. Before I do that, is there any chance the problem could be within the HVAC switch panel instead of the actuator, and if so, how can I check?

 

Additionally I'm not sure how the button for recirculate/exhaust on the blower is supposed to work. When I press it, the LED blinks and nothing happens, regardless of any other settings. Is something broken here or is it just telling me I don't have that option with the bad actuator?? Or is there another actuator for this part?

 

Am I "allowed" to chose recirculate or vent in any mode or is that only for A/C like it is in some other cars? (It doesn't seem to work with A/C either) This is my first GMT800...

[sefiroxx]

Yes, two different actuators. One is mode, the other is mix.

If both are not working, then either dash controller or common ground is bad. The actuator can be bench tested with a 12v battery.