2002 Chevrolet Blazer’s AC won’t blow out of front vents

What would be making the ac not blow out of the front vents but does blow out of the back? It makes a tick, tick, tick noise!

There’s a problem with the vent door actuator. The ticking means it’s trying to reposition the door that directs the air but failing. Either a dealer or a good independent mechanic should be able to fix it.