Sinclair SDV5 Series Service Manual page 63

2.18.4 Possible causes
 Temperature sensor/switch not
connected properly or has malfunctioned.
 Insufficient refrigerant.
 System blockage.
2.18.5 Procedure
Discharge pipe
and/or discharge temperature switch
connections on main PCB are loose
Compressor top temperature sensor
and/or discharge pipe temperature
sensor have short circuited or failed
Insufficient refrigerant caused by
refrigerant leakage
The system is blocked, caused by crushed
or bent pipe, blocked EXV or dirty filter
The indoor load is too large
System contains air or nitrogen
The condenser heat exchange is poor
Replace outdoor main PCB
Notes:
1. 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.
2. 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..
3. 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.
4. An indoor load that is too large causes suction and discharge temperatures to be higher than normal.
5. Air or nitrogen in the system causes discharge temperature to be higher than normal, discharge pressure to be higher than normal, compressor current to
62
P4
temperature sensor
No
1
No
2
No
3
No
4
No
5
No
6
No
 Indoor load too large.
 System contains air or nitrogen.
 Poor condenser heat exchange.
 Main PCB damaged.
Ensure the sensors and switch are connected
Yes
Yes
Replace the faulty sensor(s)
Yes
Add refrigerant and inspect the system for leaks
Inspect the system and fix the error. If the filter is
Yes
blocked by ice, the piping should be cleaned
Yes
Make sure the combination ratio is less than 130%
Flush all refrigerant then vacuum the system and
Yes
recharge refrigerant. Add oil to the system if it leaks
Yes
Inspect the system and fix the error
properly