Sinclair SCV-750EB Service Manual page 113

For SCV-900EB and SCV-1800EB
Outdoor ambient temperature sensor T4
connection on main PCB is loose
Outdoor ambient temperature sensor T4
has short-circuited or failed
Notes:
3. T4 temperature sensor connection is port CN1 on the main PCB (labeled 29 in Part 4, 2.2.1 Main PCB component).
4. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance
characteristics table, the sensor has failed. Refer to Table 5-5.1 in Part 5, 5.1 "Temperature Sensor Resistance Characteristics".
PH
1
No
2
No
Replace main PCB
Yes Ensure the sensor is connected properly
Yes
Replace the sensor
111