Sinclair SCV-750EB Service Manual page 108

Procedure
Water side heat exchanger water inlet /
outlet temperature sensor is loose
Water side heat exchanger water inlet /
outlet temperature sensor has
short-circuited or failed
Water piping contains air
The water flow rate is not sufficient, caused
by crushed or bent water piping, pump
capacity or high resistance in water piping
Replace outdoor main PCB
Notes:
1. For SCV-900EB and SCV-1800EB, water side heat exchanger water inlet temperature sensor and water side heat exchanger water outlet temperature
sensor connections are port CN4 on the main PCB (labeled 29 in Part 4, 2.2.1 Main PCB component). For SCV-900EB and SCV-1800EB, water side heat
exchanger water inlet temperature sensor and water side heat exchanger water outlet temperature sensor connections are port CN31 on the main PCB
(labeled 31 in Part 4, 2.2.1 Main PCB component);
2. 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".
106
P9
1
No
2
No
No
No
Ensure the temperature sensor is
Yes
connected properly
Yes
Replace the temperature sensor
Yes
Purge air from the water system
Yes
Inspect the system and fix the error