Hitachi UTOPIA RAS-4HVRP2E - Page 228

10 Troubleshooting
Initial troubleshooting
SMGB0136 rev.0 - 07/2021
226
Phenomenon
InsufcientCooling
Operation
Excessively
low suction
pressure
Indoor heat load is larger than
cooling capacity
Cause
Check Item
Action (Turn OFF
Main Switch)
Calculate heat load
Use larger unit
Use correct pipes
Remove clogging
Remove clogging
Cleanairlter
Remove obstacles
Replace fan motor
Remove cause of short-
circuited air
Replace connector
Replace coil
Replace thermistor
Correctly install it
Replace strainer in indoor
unit
Replace check valve for
outdoor unit
Correctly charge refrigerant
after repairing gas leakage
Measure superheat
Measureandcheckeld-
supplied pipes
Check whether or not
temperature difference exists
before/after check valve
Check for clogging
Check for connection 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 strainer
Check temp difference
Checkforcloggedairlter
Check for obstacle at inlet
or outlet
Insufcientrevolutionof
indoor unit fan motor?
Check Short-circuited indoor
unit air
Gas leakage
or shortage of
refrigerant
Excessively
small diameter
tube or long
piping
Incorrect
activation of
check valve of
Outdoor Unit
Failure or
malfunction
of electronic
expansion
valve
Clogged
strainer in
Indoor Unit
clogging at low
pressure piping
Clogging at low
pressure piping
Insufcientat
low pressure
piping
Excessively
low air
temperature
to Indoor
Unit Heat
Exchanger
Activation of motion sensor
control
“Motion sensor is activated”
is indicated on wired
controller.
It is normal