Display shows dF and the unit may be stuck in defrost or not cooling during this time.

Safety first: Disconnect power before accessing the control board.

Initial step: In many Summit models, dF briefly appears when the unit enters a normal defrost cycle. If it remains for an extended period and cooling stops, there may be a fault.

• Power cycle the refrigerator by unplugging it for 5 minutes, then plugging it back in.
• Monitor whether the compressor restarts and cooling resumes.

If dF persists:

• Inspect the evaporator thermistor and defrost components for shorts or damage.
• Check the main control board for signs of a stuck or burned defrost relay.

Repair: Replace any shorted sensors or a defective main control board. If you are not experienced with electronic diagnostics, contact a professional technician.