[greggats]

I pulled apart the freezer bottom panel and the fan works fine, but there is ice built up under the styrafoam panel .is the heat element bad or the therm. kit need to be replaced.. how will i know/ thanks greg

[woodchuck]

It could also be the defrost timer.tbf15sf Parts List

Turn the timer until unit turns off then see if the heater comes on and melts the ice. after 20 minutes the timer should turn the unit back on and the heater off. Check timer, heater and thermostat here. Refrigerator Repair Guide: How To Fix a Refrigerator - ACME HOW TO.com

[greggats]

how do I turn the timer off/ and if I do and the timer does not turn unit back on would that be my problem... and i was wondering were the timer is? anse i

[woodchuck]

The defrost timer is usually found behind the front grill of the freezer. It may also be found behind a cover plate inside the freezer, in the temperature control console, or behind the freezer near the compressor.

To test whether the defrost timer is simply failing to advance, locate the advance screw and turn it clockwise until you hear it click. This advances it to the next mode. If it was cooling before, it is now in defrost mode. Simply wait about 35 minutes and check whether it has left defrost mode and has resumed cooling (listen for the compressor). If it does not advance, the timer motor is probably bad and the entire timer needs to be replaced.