air condtioner ducting front a/c 98 Bounder

The air cond registers (4 front ones) don't seem to have hardly any air flow. the ones behind the a/c unit do. I see the evaporator tilts towards the back, so I'm assuming the air flow has to go back and around the unit to get to the front registers. Still their should be more air flow. Anyone had blockage in ducting and how do you check that? Thanks Oh, by the way, it cools good, but in the middle of the day (90deg), not very cool up front. The rear a/c is a killer, you can hang meat in the rear.