2002 rendezvous blower motor barely blows

Check good voltage and ground for blower motor. Actuators under the dash may be restricting air flow? High speed doesn't usually use a resister.
Check for hvac trouble codes, in my part of the country, some of the national brand autostores will check codes for free, if there are any.
If you think problem with blower motor, itself, replace it. Sometimes, you can remove blower motor, use jumper wires for voltage and ground, using inline fuse, come off the battery, see if it blows like you think it should?

Try changing cabin filter in clove box.. mine would barely blow, changed cabin filter for about $14 and work perfect.

there is a resister next to the blower motor pull it out and look for burned spots and over heated connectors

sounds like your feeling air flow from motion your blower dosen't sound like its coming on try when you are sitting still with car running turnibg on the blower if it dosen't come on it could be anything from a bad fuse to a bad blower motor

blower resister bad

You have a bad blend door motor. The dash has to be removed to do it depending on it's location.

It sounds like you have a vacuum leak. When there is no vacuum present to acutate the system, it will default to air only coming from the defrost vents. Is the blower motor operating or is the 'no air' you're talking about just no air blowing? If it's not blowing, check your fuse; if that's good, check for voltage at the blower connection. If you have voltage at the connection, remove the resistor to make sure it isn't bad befor condemning the blower motor.

Check blower motor fuse.

can you hear the fan working on all speeds?

no, did you replace the passenger cabin filter? chance are it is to late...i just found out today it is best to bc it puts pressure on the blower....its in the glove box..