The evaporator coil in the freezer would cake up with ice, choking off the cold air flow into the lower refridgerator compartment. A repair man had previously replaced the defrost heater element, but this did not fix the problem.

First, unplug the refrigerator since you're working with live wires.

Remove the 4 Philips sheet metal screws holding the plastic housing that holds the temperature control to the top of the refrigerator compartment. Pull the housing down then out since there is a tube on the housing where the water flows out the back of the refrigerator during the defrost cycle.

Remove the 2 Philips screws holding the defrost timer on the plastic housing. Pull the connectors off the old timer and attach them in exactly the same positions on the new defrost timer.

Attach the new defrost timer to the plastic housing with the 2 screws.

Reinstall the plastic housing, making sure the water tube is inserted into the back of the refrigerator wall.

Plug the refrigerator back in and you're done.