Hitachi UTOPIA RAS-4HVRP2E - Page 233

10 Troubleshooting
Initial troubleshooting
SMGB0136 rev.0 - 07/2021
231
10
Phenomenon
InsufcientHeating
Operation
Excessively
High Discharge
Pressure
Non-
condensate gas
in refrigerant
cycle
Excessively
charged
refrigerant
Clogging of
discharge piping
Excessively
high suction
pressure
Failure of
bypass solenoid
valve
Malfunction or
internal leakage
of reversing
valve
Malfunction or internal leakage of
reversing valve
Malfunction of check valve of
outdoor unit
Discharge temperature of Indoor
Unit is Unstable
Insufcientair
owtoindoor
unit heat
exchanger
Excessively high
air temperature
to indoor unit
heat exchanger
Cause Check Item
Checkforlterclogging
Check for any obstacles at
inlet or outlet of indoor unit
Remove clogging
Action (Turn OFF
Main Switch)
Replace fan motor
Remove cause of short-
circuited air
Correctly charge refrigerant
Recharge refrigerant after
vacuum pumping
Replace failed expansion
valve of indoor unit
Remove clogging
Replace reversing valve
Replace check valve
Replace solenoid valve
Replace reversing valve
Remove obstacles
Check temperature
difference at inlet and outlet
of check valve
Check temperature
difference at inlet and outlet
of reversing valve
Check for clogging
Check each temperature and
pressure
Check expansion valve
opening
Check short-circuited air to
indoor units.
Check indoor fan speed
Check for leakage of
solenoid valve
Check temperature
difference between inlet and
outlet of reversing valve
Check for expansion valve
of indoor unit in the same
system
Activation of motion sensor control
“Motion sensor is activated”
is indicated on wired
controller
It is normal