So my 1997 ranger 4cyl. had no heat. replaced heater control valve(it was loosing fluid). still no heat. Pulled the blend motor(frozen solid), checked blend door(no coupling showing at all). So its broke no nail fix. Call me lazy or call me tired of being cold. I cut a hole in the bottom of the Heater box, flipped the blend door by hand. I know no cold air in the summer but the A/C doesnt work and i needed heat. Maby ill fix it the right way this spring before it gets to hot, or ill flip the blend door back to cold if im still feeling lazy.
Over all it is not that hard just time consuming. The hardest part was wrestling the steering column.
My heater core was partially plugged which is why I also replaced the blend door.
Old temporary fix
That whole box is glued together so you have to get a kit to fix it. You need to cut a hole to remove the blend door, put the new one in then block it off with a supplied metal plate. One thing you should do which I forgot to do is trim the foam seal on the blend door a little bit, you don't need to over do it, without doing that the resistance to turn is very high which is why they break.