Sinclair SCV-750EB Service Manual page 89

For SCV-900EB and SCV-1800EB
High pressure switch or discharge
temperature switch connection on main
High pressure switch or discharge
temperature switch have short-circuited or
The high pressure side is blocked, caused
by crushed or bent pipe or blocked EXV
The heat exchange is poor
The water flow rate is not sufficient in
Replace outdoor main PCB
Notes:
1. High pressure switch connection is port CN20 on the main PCB (labeled 19 in Part 4, 2.2.1 Main PCB component).
2. Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor has
failed.
3. High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to
be lower than normal.
4. In heating mode check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. In cooling mode check air side
heat exchanger, fan(s) and air outlets for dirt/blockages.
P0
PCB is loose 1
No
failed 2
No
No
4
No
cooling mode
No
Ensure High pressure switch or discharge
Yes
temperature switch are connected properly
Replace the high pressure switch or
Yes
discharge temperature switch
Yes
Inspect the system and fix the error
3
Yes
Inspect the system and fix the error
Yes
Inspect the water system and fix the error
87