Sinclair SCV-750EB Service Manual page 111

Procedure
Low pressure sensor connection on main
Low pressure sensor has short-circuited or
Insufficient refrigerant caused by
refrigerant leakage
The low pressure side is blocked, caused by
crushed or bent pipe, blocked EXV, or dirty
The air side heat exchanger heat exchange
is poor in heating mode
The water flow rate is not sufficient in
Notes:
1. For SCV-750EB and SCV-1400EB, low pressure sensor connection is port CN42 on the main PCB (labeled 27 in Part 4, 2.2.1 Main PCB component). For
SCV-900EB and SCV-1800EB, low pressure sensor connection is port CN16 on the main PCB (labeled 30 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. To check for insufficient refrigerant: An insufficiency of refrigerant causes compressor discharge temperature to be higher than normal, discharge and
suction pressures to be lower than normal and compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. These
issues disappear once sufficient refrigerant has been charged into the system;
4. A low pressure side blockage causes compressor discharge temperature to be higher than normal, suction pressure to be lower than normal and
compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. For normal system parameters;
5. Check air side heat exchanger, fan(s) and air outlets for dirt/blockages;
6. Check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages.
PC
PCB is loose 1
No
failed 2
No
3
No
filter 4
No
5
No
cooling mode 6
No
Replace main PCB
Yes Ensure the sensor is connected properly
Yes
Replace the sensor
Add refrigerant or inspect the system for
Yes
Inspect the system and fix the error. If the
Yes
filter is blocked by ice, the piping should be
Inspect the refrigerant system and fix the
Yes
Yes
Inspect the water system and fix the error
leaks
cleaned
error
109