Dehumidifier displays P3 and compressor will not engage

Safety first: Unplug the unit before moving or opening any panels.

Steps to resolve P3:

• Check room temperature: Use a separate thermometer to verify the room is within the unit's specified operating range (typically around 41°F–95°F / 5°C–35°C for many Whynter dehumidifiers). If the room is too cold, relocate the unit or raise the room temperature.
• Relocate the unit: Move the dehumidifier away from cold windows, exterior doors, or unheated basements where cold drafts may affect the sensor.
• Power reset: Unplug the unit for 5 minutes, then plug it back in and restart. This can clear temporary sensor reading errors.
• Inspect thermistor connection: If accessible on your model, remove the front or side panel (after unplugging) and locate the ambient thermistor clipped near the air intake. Ensure its connector is firmly seated on the control board and the sensor is not dangling or touching the evaporator coil directly.

If P3 persists in a room that is clearly within the correct temperature range, the ambient thermistor or main control board may be faulty and should be tested or replaced by a technician.