Display shows HI and unit may run continuously or struggle to reach set temperature.

Safety: Minimal disassembly required.

• Confirm room temperature: Use a thermometer to verify actual room temperature. If the room is extremely hot, improve ventilation and reduce heat sources.
• Check sensor placement: Ensure the ambient sensor is not touching warm metal parts or located near the condenser discharge air.
• Inspect and test sensor: If HI appears in a normal-temperature room, test the room thermistor resistance. Replace if out of specification.