I just replaced my heater core, got the dash all put back together and went to test everything out and I relized even when i turn my **** the air vents don't change. Air will only come through the windshield defrost vent. I tried to turning it to floor and it still stayed through the windshield. you guys have any ideas to what might have happened?

 

Vacuum line. The default position (with no vacuum) is defrost. Look under the dash for broken lines.

 

I figured that out right after I posted that