Excessive frost or ice buildup on the back wall or around the evaporator.

Safety: Unplug the unit before defrosting or accessing the evaporator. Do not use sharp tools to remove ice.

• Manual defrost: Turn off and unplug the cooler. Open the door and allow all ice to melt. Use towels to absorb water.
• Inspect door gasket: Check for tears, gaps, or warping. Replace the gasket if it does not seal tightly all around.
• Access evaporator and defrost components: Remove the interior rear panel to expose the evaporator coil, defrost heater, and thermistor.
• Test defrost heater: With the unit unplugged, disconnect the heater and measure resistance. Infinite resistance indicates a failed heater that must be replaced.
• Test defrost thermistor: Measure resistance and compare to other sensors. Replace if open or shorted.
• Control board evaluation: If heater and sensor are good, the defrost control on the main board may not be initiating defrost cycles. Replace the board if necessary.
• Reassemble and monitor: After repairs, reassemble and monitor for several days to ensure frost does not return.