2013 Prius front defogger doesn't blow air

I just noticed this problem a few days ago when my window shield kept fogging despite having the defrost on for a long time. I put my hand up to check and no air is coming out in front of the windshield. I checked the in cabin air filter behind the glove box but it seemed pretty clean. I shook it out and replaced it and I still have no air. My other vents seem to be working okay, and the car will heat, just not the defogger. I hear the mechanism when switching modes but nothing comes out from underneath the windshield.

Any ideas that I can try to fix myself? I'm not looking forward to having to take it in for this. I live in the upper Midwest so this feature is a killer. Thanks.

 

I'm not sure the difference. I usually just press the front defrost button to defrost the windshield. But neither option triggers the vents underneath the windshield to blow air.

 

Thanks, I'm just trying to make sense of it. It's huge.