Heater A/C Control Unit

I own a 95 chevy 1500 truck and I've replaced the unit for the second time. I'm trying to figure out why the vents are not closed when the fan is not on. The red LED on the button doesn't even light up when it's closed and it should because the original controller did that. I mean when i cut it on, i can hear the vents close or shift i guess, the LED lights up but that's when it's on right, if i open the vent, there should be a drop on how hard the fan blows but it's not. It's stays the same whether i open or close it and the original controller didn't do that. Does anybody know what could be the problem because it sure isn't the brand new controller i've bought?