Display alternates dF and temperature; unit may stop cooling periodically and ice may build up.

Safety: Unplug the cooler before working on the evaporator or control board.

Steps:

• Observe behavior: A brief dF indication during normal operation can be normal. If dF remains for hours and cooling is poor, there is a fault.
• Check evaporator: Remove the interior rear panel. Heavy ice buildup indicates defrost failure; a warm, wet evaporator with no cooling suggests the unit is stuck in defrost.
• Test defrost sensor and heater: Follow the testing steps described under E5 to verify both components.
• Reset control: After testing, unplug the unit for 10 minutes to reset the control logic. If dF returns and the unit does not cool, the main PCB may be defective.
• Replace parts: Install a new defrost heater or defrost sensor if faulty. If both are good, replace the main control board.

Warning: Do not bypass the defrost system; this can cause severe ice buildup and damage.