no air coming out of vents with heater or air conditioner

I recently replaced the blower motor for my heater and air conditioner. After replacing the motor there is little to no air coming out of the vents. I can hear the motor speed increase or decrease as I manipulate the speed dial, but very little air is coming out of the vents. I have tried this using all of the positions for the air (defrost,/floor, floor, etc.) and the same amount of air is moving. I am wondering if you have any idea what the problem may be.