My buddy has a 97 Sahara and the defrost does not work, it only blows out the vents. We pulled the dash out over the weekend and discovered that the flap that changes the flow of air has broken where the vac. control hooks to it. Do you have to buy the whole heater core box or is there some way to replace just the flap? We tried epoxy but it only made it work for a few seconds before it broke free again!