Sinclair SCV-750EB Service Manual page 109

5.17 Pb Troubleshooting
Digital display output
Description
Water side heat exchanger anti-freeze protection.

All units stop running.

Error code is displayed on main PCB and ANTI.FREEZE icon is displayed on user interface.

Possible causes
Normal system protection.

Temperature sensor not connected properly or has malfunctioned.

For SCV-750EB and SCV-1400EB, main PCB or slave PCB damaged;

For SCV-900EB and SCV-1800EB, main PCB damaged.
Procedure
Min(Tw/Two/Twi/Taf) ≤ 4°C for 5s in normal
cooling mode or min(Tw/Two/Twi/Taf) ≤
-1°C for 5s in low water outlet mode
Tw/Two/Twi/Taf temperature sensor loose
Tw/Two/Twi/Taf temperature sensor has
short-circuited or failed
Replace outdoor main PCB
Notes:
1. For SCV-750EB and SCV-1400EB, combined Water side heat exchanger water outlet temperature sensor(Two), water side heat exchanger water inlet
temperature sensor (Twi) and water side heat exchanger anti-freezing temperature sensor(Taf2) connections are ports CN4 and CN45 on the main
PCB(labeled 29,21 in Part 4, 2.2.1 Main PCB component).Water outlet temperature sensor (Tw) connections is ports CN101 on the slave PCB (labeled 14 in
Part 4, 2.7 Slave PCB component).
2. For SCV-900EB and SCV-1800EB, combined water outlet temperature sensor (Tw), Water side heat exchanger water outlet temperature sensor(Two), water
side heat exchanger water inlet temperature sensor (Twi) and water side heat exchanger anti-freezing temperature sensor(Taf, include Taf1 and Taf2)
connections are ports CN31 and CN69 on the main PCB (labeled 31,32 in Part 4, 2.2.1 Main PCB component).
3. Refer to Part 3, 6.7 "Water Side Heat Exchanger Anti-freeze Protection Control".
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 Part 4, 6.1 "Temperature Sensor Resistance Characteristics".
Pb
1
No
No
3
No
Normal system protection. The system will
Yes
resume automatically
Ensure the temperature sensor is
Yes
connected properly
Yes
Replace the temperature sensor
2
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