A/C air is cold but air coming out defrost vents instead of cab

It sounds to me like the actuator. It’s ablittle motor with a gear attached to it. When you turn the knob from defrost to cabin,it powers the actuator and it moves position. It’s attached to a plastic flap usually that moves and directs the air one way or another. If your sure the knob isn’t messed up,it’s very likely the actuator.

This happened in my parents’ van with the rear air. The plastic flap got stuck between ceiling and floor air. After disassembling the air ducts,I found the actuator,replaced it,and it worked again.

All all cars are designed a bit diffeeently. But the actuator for front air is right behind the front compartment. The actuator is basically designed to be powered and move one way or the other,to move the plastic flap. The motor inside goes bad after years of usage. Replacing this is very likely to solve your issue…but it could also be a power issue where power isn’t getting to the actuator,or something came loose,such as the plastic flap that the actuator controls.

I don’t know much about cars. But this is what the problem sounds like to me,especially if it happened suddenly. YouTube is the best source to check out for videos. The actuator replacement is available online,but if you find a junk yard,the part can cost 1/10th of what it would new. Some junk yards offer a credit if the part doesn’t work at all. My dad and I went to a junkyard for this reason.

If you attempt it,be careful and if something doesn’t want to come out,take your time. Hidden bolts,or plastic tabs are likely blocking it coming out.

good luck!