Sinclair SDV5 Series Service Manual page 59

2.16.4 Possible causes
 Pressure sensor/switch not connected properly or has malfunctioned.
 Excess refrigerant.
 System contains air or nitrogen.
 High pressure side blockage.
 Poor condenser heat exchange.
 Main PCB damaged.
2.16.5 Procedure
High pressure sensor connection on main
High pressure sensor has short-circuited or
System contains air or nitrogen
The high pressure side is blocked, caused
by crushed or bent pipe or blocked EXV
The condenser heat exchange is poor
Replace outdoor main PCB
Notes:
1. 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.
2. Excess refrigerant causes discharge temperature to be lower than normal, discharge pressure to be higher than normal and suction pressure to be higher
than normal.
3. Air or nitrogen in the system causes discharge temperature to be higher than normal, discharge pressure to be higher than normal, compressor current to
be higher than normal, abnormal compressor noise and an unsteady pressure meter reading.
4. 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.
5. In cooling mode check outdoor heat exchangers, fans and air outlets for dirt/blockages. In heating mode check indoor heat exchangers, fans and air outlets
for dirt/blockages.
58
P1
PCB is loose
No
1
failed
No
2
Excess refrigerant
No
3
No
No
No
Yes
Ensure the sensor is connected properly
Yes
Discharge part of the refrigerant. Add oil if
Yes
Flush all refrigerant then vacuum the
Yes
system and recharge the refrigerant. Add
Yes
Inspect the system and fix the error
4
Yes
5
Inspect the system and fix the error
Replace the sensor
it leaks during discharge
oil to the system if it leaks