Freezer beeps and displays E1, temperature fluctuates or does not reach set point

Safety first: Unplug the Montpellier freezer from the mains before removing any panels. Do not work on live circuits.

• Power reset: Disconnect power for 5–10 minutes, then reconnect. If E1 clears and does not return, it may have been a transient fault.
• Locate the cabinet sensor: On most Montpellier upright and chest freezers, the cabinet NTC is clipped behind the inner liner or in a small plastic housing on the rear wall inside the freezer. Remove the relevant cover or inner panel screws carefully.
• Inspect wiring: Check the sensor leads from the probe to the cabinet harness. Look for cuts, crushed insulation, or pulled connectors. Reseat any loose plugs at the sensor and at the main PCB (usually behind the rear lower service panel).
• Test the sensor: With a multimeter set to resistance (ohms), measure the NTC at room temperature. Typical NTCs read between 5–20 kΩ at ~25°C. If it reads open circuit (OL) or 0 Ω (short), the sensor is faulty and must be replaced.
• Replace the sensor: If readings are out of spec, install a compatible Montpellier cabinet NTC sensor. Route the new sensor along the original path and secure it away from moving parts or sharp edges.
• Check the PCB connector: If the sensor tests good, inspect the main control board connector for corrosion or burning. Clean lightly with contact cleaner and reseat.

If E1 persists with a known-good sensor and wiring, the main control board is likely defective and should be replaced by a qualified technician.