Sinclair SCV-750EB Service Manual page 93

Procedure
The power supply is abnormal
System contains air or nitrogen
The condenser heat exchange is poor
The high pressure side is blocked, caused
by crushed or bent pipe or blocked EXV
Inverter module has short-circuited
Compressor has malfunctioned
Replace outdoor main PCB
Notes:
1. 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.
2. 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.
3. Set a multi-meter to buzzer mode and test any two terminals of P N and U V W of the inverter module. If the buzzer sounds, the inverter module has
short-circuited.
4. The normal resistances of the inverter compressor is 0.124Ω(at 20℃ ambient temperature) among U V W and infinite between each of U V W and ground.
If any of the resistances differ from these specifications, the compressor has malfunctioned.
P4/P5
No
Excess refrigerant
No
No
No
No
No
4
No
Yes
Check the power supply equipment
Discharge part of the refrigerant. Add oil if
Yes
it leaks during discharge refrigerant process
Flush all refrigerant then vacuum the
Yes
system and recharge refrigerant. Add oil to
Yes
1 Inspect the system and fix the error
Yes
Inspect the system and fix the error
2
Yes
3
Yes
the system if it leaks
Replace the inverter module
Replace the compressor
91