Hisense Hi-Therma Series Service Handbook page 328

Phenomenon
Excessively high
discharge pressure
Insufficient cooling
process
Malfunction or internal leakage of the 4-way
reversing valve
Excessively low
suction pressure
Discharge temperature of the outdoor unit is
unstable
Cause
Clogging of the outdoor unit heat
exchanger?
Obstacles at the inlet or the outlet
Insufficient air flow at
of the outdoor unit heat exchanger
the outdoor unit heat
exchanger
Is the service area for the outdoor
unit sufficient?
Correct fan speed?
Short-circuited air to the outdoor
Excessively high air
unit?
temperature to the
outdoor unit heat
Any other heat load near the
exchanger
outdoor unit?
Excessively charged
Expansion valve opening
refrigerant
Non-condensated gas Check each temperature and each
in cycle pressure
Clogging of the
Check for clogging
discharge piping
Check for clogging
Check the connection cord and
the connector
Is there an operation sound from
Failure or malfunction
the coil?
of the expansion valve
Is the thermistor on the
compressor normal?
Is the thermistor installed correctly
on the compressor?
Check the temperature difference
at the inlet and the outlet of the
4-way reversing valve
Malfunction or internal Check the temperature difference
leakage of the 4-way between the inlet and the outlet of
reversing valve 4-way reversing valve
Check the expansion valve of the
outdoor unit
307
Check item
(Turn OFF the main switch)
Remove the clogging
Remove the obstacles
Secure the service area
Replace the fan motor
Remove the cause of the short-
circuited air
Remove the heat source
Correctly charge the refrigerant
Charge the refrigerant after the
vacuum pumping
Remove the clogging
Remove the clogging
Replace the connector
Replace the coil
Replace the thermistor
Correctly install the thermistor
Replace the 4-way reversing
valve
Replace the 4-way reversing
valve
Replace the failed expansion
valve of the outdoor unit
Troubleshooting
Action