light on inside, fridge and freezer warm up after initially cooling

Fridge/freezer warm. After unpluging and plug in again, both would get cold. Then, ice would partially melt in the freezer only to refreeze later. Noted large temperature swings in freezer-up to 48 degrees during defrost cycle. Finally after a day or two, both sides warming up permanently to room temp. Tapping inside the fridge near the cold control (thermostat) would cause the warm fridge/freezer to cool again. Installation is simple. Remove knobs and snap on face plate in front top of fridge. Remove screws allowing plastic cover to drop down which houses the thermostat at the inside top of fridge. loosen two mounting hex head screws from thermostat mount. Remove two plastic covers concealing thermostat wire that travels to vent at back of fridge. Remove thermostat. remove plastic tube over wire on old thermostat by slipping it forward and slide tube on to new thermostat wire. Install is the same in reverse. A thermometer in the freezer confirms very little temperature variation after install (3-4degrees); ice no longer melts, unit stays on!