95 S10 Heat/Vent problem

Hi everyone,
I'm new to this site.
I have a '95 S10 Pick-Up.
My heat has not been working correctly.
It seems as though the vent is stuck open.
Today when it snowed, my defrost was blowing snow inside my truck. Some snow also came out the passenger side lower heat vent?

Can anyone tell me what I need to do to fix this?!

I don't know if maybe the vent is stuck open from the cold weather. Could I possibly close this by hand somehow?

Any help would be greatly appreciated!!

If you are getting snow inside the outside vent is not closing.
How long has the heat been acting up?
Things to check first is good engine vacuum to heater controls.
Always check the vacuum ball and hoses and plastic lines to and threw it.
Check for a broken plastic line.

Does your heater switch good from defrost to dash air vent to floor heat?
Does it switch good from hot to cold?

If all of that is good find the outside air vent and see if door is opening and closing.
Also it could be froze up with ice or water or tree leaves.
If you can get it in inside garage and warm it up good.

Good Luck and let us know how it goes.

It was working fine before it got really cold out, which makes me think it's froze open. I do not have a garage to put it in to warm it up right now.
The vacuum lines are fine, best I can tell.

How do I get to the vent to try and move it by hand?

Hope for a good warm day or to.
Also check it for drains in the outside vent area.
They could be stopped up holding water in there.
Good Luck