2001 Blazer has little air going to defrost and floor. Almost all air out of vents. All vacuum lines seem to be intact & in good shape. Had to take dash apart before to replace heater core. No lines or wires seem to be pinched anywhere. Any help would be appreciated, Thanks!

 

did you look at the vac line going from intake manifold, over the brake booster and t's to the vaccum tank?

 

. You the man BB, it was hose that collapsed on itself, was hidden behind brake booster