Hitachi UTOPIA RAS-4HVRP2E - Page 229

10 Troubleshooting
Initial troubleshooting
SMGB0136 rev.0 - 07/2021
227
10
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
Check clogging of Outdoor
Unit Heat Exchanger
Obstacles at inlet or outlet of
outdoor unit heat exchanger?
Secure service space
Replace fan motor
Remove cause of short-
circuited air
Remove heat source
Correctly charge refrigerant
Charge refrigerant after
vacuum pumping
Is service space for outdoor
unitsufcient?
Correct Fan Speed?
Short-circuited air to Outdoor
Unit?
Any other heat load near
Outdoor Unit?
Check expansion valve
opening
Check each temperature and
pressure
Check for clogging
Check for clogging
Check for connecting cord
and connector
Is there operation sound
from coil?
Is thermistor on compressor
normal?
Is thermistor installed
correctly on compressor?
Check temperature
difference at inlet and outlet
of reversing valve
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
Replace failed expansion
valve of indoor unit
Remove clogging
Remove clogging
Remove clogging
Remove connector
Replace coil
Replace thermistor
Correctly install it
Replace reversing valve
Replace solenoid valve
Replace reversing valve
Remove obstacles
Insufcient
Cooling
Operation
Excessively
high
discharge
pressure
Insufcientair
owtooutdoor
unit heat
exchanger
Excessively
high air
temperature
to Outdoor
Unit Heat
Exchanger
Excessively
charged
refrigerant
Non-condensed
gas in cycle
Clogging of
discharge
piping
Failure or
malfunction
of expansion
valve
Malfunction or internal leakage of
reversing valve
Excessively
low suction
pressure
Discharge temperature of Indoor
Unit is Unstable
Failure of
bypass
solenoid
Malfunction or
internal leakage
of reversing
valve