Air stopped blowing through vents, only blows through defroster

You do not mention the type of car you have. If you have air that blows out the defroster and panel vents you should have defrost. Do you smell a sweet odor coming from the car? This could be antifreeze leaking though the heater core. This will cause your windshield to remain foggy.

Usually this is a problem with the blend doors under the dash. You either have a vac leak, a dead motor, or a faulty door.
The control opens and closes the doors to direct air thru the heater core and evaporator core along with directing air thru the vents.
When a problem occurs, the default position is the defrost vents to make sure the windshield remains clear.
You can do an internet search for "repair durango blend door" for more info.

Common question on this site. On late model cars, the vents are controlled by blend door motors. Small electric motors open and close doors to direct air flow.
Chances are you have a blend door that is stuck or a failed motor.
The default position is the defrost to make sure the windshield is always clear.
Someone will need to look behind the dash to see if all of the doors will move on demand.

i believe this is a vacuum operated system. if there is a problem with the vacuum supply to the control unit, it will automatically default to defrost. i would start by checking the vacuum source lines. good luck!

behind the center counsel between the floor and the heater housing is a part that is called the blend door actuator. these usually go bad and have to be replaced.

It's normal for the A/C compressor to come on with the defroster to dehumidify the air so the windsheild won't fog up under humid conditions. You can still control the air temp. out the vents with the temp. select switch.

AC blows where you have your control switch set,if it only comes out your defroster have the vacuum check at the blend air doors or if you have a faulty heater control unit.

I had this same problem. Your blower is going out. Just replace the blower. Its a siple fix, and its pretty cheap.

If you have the heater directed to the windshield, the AC will turn on. Move the control away from defrost.