Refrigerator shows H21, temperature readings are inaccurate or fluctuating, cooling cycles seem abnormal

Safety: Unplug the refrigerator before accessing internal panels.

• Step 1 – Locate refrigerator thermistor: In Panasonic models, the refrigerator thermistor is typically clipped to the liner wall or mounted near the evaporator behind the rear interior panel.
• Step 2 – Inspect sensor and wiring: Remove the inner panel as needed. Check that the thermistor bulb is intact and firmly clipped in place. Inspect the wiring harness for cuts, pinches, or rodent damage.
• Step 3 – Connector check: Disconnect and reconnect the thermistor plug to clear any oxidation. Ensure a snug fit.
• Step 4 – Resistance test (if you have a multimeter): At room temperature (~25°C), most Panasonic NTC thermistors read around 5–10 kΩ. If the reading is infinite (open) or near 0 Ω (short), replace the thermistor.
• Step 5 – Replace thermistor: Install a genuine Panasonic refrigerator thermistor, routing the wires as originally to avoid contact with moving parts or sharp edges. Reassemble panels and restore power.