hey there folks. I have a 2000 blazer 4.3l motor. i am currently having a issue with my heater controls. i have a manual heater controls and my defroster, floor setting does not work. i was wondering how to test the actuators and what to look for if theres a issue with them.

 

The usual problem with the defroster/floor vents not working is the door inside the air distributon box behind the dash.
Do a search for "defroster valve" and see if that is it.

Also look at the actuator right above the accelerator pedal. There is white plastic shaft attached to it. See if anything here is broken. This is the defroster valve.

Good luck.