Dehumidifier shows E7 and shuts down; fan may still operate.

Safety: Unplug the unit before accessing internal components.

Steps:

• Allow full defrost: If the evaporator is iced, let the unit sit unplugged until all ice melts.
• Access evaporator area: Remove front housing and bucket to expose the evaporator coil and sensors.
• Identify defrost sensor: Some Challenge models use a separate NTC sensor for defrost, clipped to the lower part of the evaporator or suction line. It may be bundled with foam insulation.
• Inspect and reseat: Check that the sensor is firmly attached and its wires are intact. Reseat the connector on the main PCB.
• Test sensor: With a multimeter, measure resistance at room temperature and compare to the ambient sensor if they are the same type. A reading of 0 Ω or infinite indicates failure.
• Replace if faulty: Install a compatible Challenge defrost temperature sensor, routing the wires as originally and securing the sensor to the coil or line.
• Reassemble and test: Refit covers, plug in, and run the unit. If E7 remains, the defrost control circuit on the PCB may be defective and require board replacement.