Hitachi UTOPIA RAS-4HVRP2E - Page 239

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
237
10
Phenomenon Cause Check item
Action (Turn OFF the
main switch)
Activation of the
high-pressure
switch due to the
excessively high
discharge pressure
(PSH)
Outdoor Unit:
InsufcientAirFlowtotheHeatExchanger(Outdoor
Heat Exchanger during the Cooling Process)
Indoor Unit:
Indoor Heat Exchanger (during the Heating Process)
Check the heat
exchanger for dust or for
clogging
Remove the dust or the
clogging
Checktheairlterfor
dust
Remove the dust
Check for any obstacles
at the inlet or the outlet of
the heat exchanger
Remove the obstacles
Check the service area Secure service area
Check the speed
(Outdoor Fan: Cooling)
Replace the fan motor if
faulty
Check the speed of the
water pump
Replace the water pump if
faulty
Expansion valve malfunction or abnormality
Disconnected
Fix the looseness or
reconnect the connector
Fully closed and locked
Replace the expansion
valve
Check the operation
sound of the coil
Replace the coil
Check the Discharge Gas
thermistor
Replace the thermistor
Check the fastening of
the thermistor
Re-fasten the thermistor
Faulty High-Pressure
Switch
Faulty Pressure Switch
Measure the discharge
pressure. Check the
continuity after the
decrease of the pressure
Replace the pressure
switch if faulty
InsufcientContacting
Measure the resistance
by means of a tester
Fix the looseness. Replace
the connector
Incorrect Connection Check the connections Repair the connections
Overcharged refrigerant
Check the cycle
operation temp.
Charge the refrigerant
correctly
Mixture of the non-condensate gas in the refrigerant
cycle
Check the air temp. and
the pressure
Recharge the refrigerant
after the vacuum pumping
Clogging of the discharge piping Check for clogging Remove the clogging
Liquid line stop valve or gas line stop valve is not in
operation
Check the stop valves Fully Open the stop valves
Faulty magnetic
contactor switch
No power is supplied to the coil Check connections
Set the connections
properly.
No power at the A contact
Measure the resistance
using a tester
Replace the magnetic
switch if it is broken