Bryant R-22 Failed Thermistor Default Operation, Outdoor Air Thermistor OAT Attachment

The thermistor comparison is not performed during low ambient cooling or defrost operation.

Failed Thermistor Default Operation

Factory defaults have been provided in the event of failure of outdoor air thermistor (OAT) and/or outdoor coil thermistor (OCT).

If the OAT sensor should fail, low ambient cooling will not be allowed and the one-minute outdoor fan off delay will not occur. Defrost will be initiated based on coil temperature and time.

OAT Thermistor must be locked in place with spherical nib end facing towards the front of the control box

If the OCT sensor should fail, low ambient cooling will not be allowed. Defrost will occur at each time interval during heating operation, but will terminate after 5 minutes.

If there is a thermistor out of range error, defrost will occur at each time interval during heating operation, but will terminate after 5 minutes.

Count the number of short and long flashes to determine the appropriate flash code. Table 23 gives possible causes and actions related to each error.

OCT Thermistor must be secured tight on stub tube.

Fig. 57 – Outdoor Air Thermistor (OAT) Attachment Fig. 58 – Outdoor Coil Thermistor (OCT) Attachment

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