heater help

[70stroker]

Guys i have a 86 chevy 4x4 shortbed. Its starting to get colder down here and I think about now is a good time to start figuring this all out. the heater gets warm but the blower doesnt seem to be putting out much.

You can hear the blower motor step up its speed with each and every selection you go up on the speed, But you cant really feel much of a difference in flow from the low up to high.

Now this truck did sit for about a year before i got it. So it could be something in the ducting, such as a nest or insulation, but im not 100% sure. If you guys think this also can anyone tell me the best way to go about taking the ducting out and installing it to make sure it all works again. Pictures would be helpful alos.

Thanks