Not enough heat blowing from the vents

Where do you live?

How old is your unit?

Is the volume of air the same as its always been?

Thanks, its always good to give as much information as you can when making an inquiry. If you give the make and model number, some of the pros that come on here can point you in the right direction based on a particular models service history. My furnace, for instance, was involved in a class action lawsuit for premature failure of its secondary heat exchanger. Keeping from us the fact that someone just put in a new blower motor does not help us help you at all. If your blower worked right before they replaced it maybe its hooked up wrong.