low air flow in ac/or heat.?

when i turn my fan on and put either the ac or heat on face fan or fan and feet. there is just a low flow of air? and lots of air blowing toward the defrost/window.
even when i don't have defrost on.
any ideals what is causing this or anyone with same problem?

This is the classic symptom of a vacuum leak. You don't state what year model, but the earlier models have a common point of failure. It is the small hard line that runs down behind the battery. You may also be noticing erratic or a high idle along with this condition.