I have no idea what could be causing this. If I put the temp to cold, it will be cold but it will stay on windshield defrost. Also, it will always blow air out of the defrost even in the off position. Does anyone know what it could be?

 

Welcome to TGO. Defrost is the default when you have a vacuum leak. More often than not, the culprit is the switch itself. Put an ear to it and listen for the hiss. If not that, the search function will provide a basket full of info.

JamesC

 

if not look for a small black plastic hose around the intake area, cracked or rubber plug split