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What actions should I take if my Ruud Ultra Plug-in Heat Pump with HydroBoost (120V Shared Circuit) displays Alarm Code A009?

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 compressor malfunction. What To Do:

  1. Check connections of the wiring and sensors.
  2. If you have a multimeter, obtain an Ohm reading on the thermistors. You should consult the Ohm chart for accurate readings based on the ambient temperature.
  3. Navigate to Service –> Sensors on the display. If the sensor displays -40°F, this indicates that the circuit is open. A display of +250°F signifies the circuit has shorted. To validate this reading, turn off the unit and disconnect the thermistor from the board, then recheck the Ohm reading.

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

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