Description
The Outdoor ambient sensor, located just below the control board is either loose or has otherwise failed.
Expected Operation
The unit will continue to run with this sensor defective. However if this is a heat pump, in heat mode, the UODC will recognize this and will default as a time-temperature defrost control until the sensor is repaired.
Cause
The most likely cause for this failure is that the sensor is not connected or that the sensor or sensor wiring or connector is failed, disconnected or broken.
Solution
1. Remove the sensor from the UODC and check the resistance against the 10k thermistor chart and the known temperature near the thermistor.
2. If the thermistor is improperly reading by degrees this fault will not occur, it will however occur if the sensor is either open or shorted or otherwise is outside normal range. If it is, replace the sensor.
3. Replace Universal UODC controller.