What should I do if my Ruud Ultra Plug-in Heat Pump with HydroBoost (120V Shared Circuit) indicates Alarm Code A101?

CAUTION: For your safety, DO NOT attempt repair of electrical wiring, controls, heating elements, or other safety devices. Refer repairs to qualified service personnel.

Possible Cause: Heating source defaults to elements due to heat pump temperature sensor malfunction. What To Do:

1. Examine the connections of the wiring and sensors.
2. If you possess a multimeter, acquire an Ohm reading on the thermistors. Remember to refer to the Ohm chart to ensure the readings align with the current ambient temperature.
3. Navigate to Service –> Sensors on the display interface. If the sensor reading is -40°F, this denotes the circuit is open. A display of +250°F reveals that the circuit has shorted. As a confirmation step, power down the unit, disconnect the thermistor from the board, and then re-evaluate the Ohm reading.

This answer is applicable for the following model: Ruud Ultra Plug-in Heat Pump with HydroBoost (120V Shared Circuit).