How to free up fresh air vent door?

If you remove a frozen Door/ hinge I have had good luck with a small punch on the dished end of the door hinge while I use a socket slightly bigger than the rounded head side of rivet. Place the socket on my vise, put the rounded end of the rivet on top of the socket and use the punch n the dished end and tap it enough to loosen the rivet a little. Of course I spray the heck out of the joints with PB. Play with it a while and it will be loose in no time.