189
TROUBLESHOOTING
9) Refrigerant Low Pressure Abnormality
For diagnosis and repair, Refer to P306 and after, [Wiring Diagram of the Outdoor Unit]
Problem Possible Cause Specific Example Inspection and Treatment
E4 (88) error
JC (88) error
U0 (88) error
In cooling
Heat exchange
at the evaporator
(indoor unit) is
disturbed
Indoor fan motor
operation failure
Obstacle
(contact with other objects)
Clean up obstacle
Indoor fan motor failure
Refer to P224, 41)Inspect In-
door Fan Motor
Indoor fan capacitor failure
Output failure
Deteriorated heat
exchange capacity
Dust or dirt on the air filters Clean air filters
Clogged heat exchanger fins
/ obstacle
Clean heat exchanger fins
Intake air tempera-
ture is too low
Short circuit, etc.
Sub heat exchanger liquid flow control valve failure
Refer to P225, 47)Inspect Sub
Heat Exchanger Liquid Flow
Control Valve
Refrigerant sys-
tem failure
Hot gas bypass
valve operation
failure
Hot gas bypass valve
operation failure
(Blockage condition)
Refer to P223, 40)Inspect Hot
Gas Bypass Valve
Blockage in the hot gas
bypass valve
Blockage in the re-
frigerant flow path
Blockage in the stop valve
In
heating
Heat exchange
at the evaporator
(outdoor unit) is
disturbed
Outdoor fan motor
operation failure
Obstacle
(contact with other objects)
Clean up obstacle
Outdoor fan motor failure
Refer to P217, 27)Inspect
Outdoor Fan Motor
Output failure
Deteriorated heat
exchange capacity
Clogged heat exchanger fins
/ obstacle
Clean heat exchanger fins
Intake air tempera-
ture is too low
Environmental / installation
conditions are severe
Refer to P224, 43)Check Envi-
ronmental Conditions (Low
Intake Air Temperature)
Deteriorated sub
heat exchange
capacity
Poor circulation of engine
coolant
Refer to P215, 24)Inspect En-
gine Coolant Pump
Thermostat failure
Refer to P216, 25)Inspect
Thermostat
Sub heat exchanger liquid
flow control valve failure
Refer to P225, 47)Inspect Sub
Heat Exchanger Liquid Flow
Control Valve
Outdoor heat exchanger liquid flow control valve
failure
Refer to P226, 48)Inspect
Outdoor Heat Exchanger Liq-
uid Flow Control Valve
Common
to
cooling/
heating
Inappropriate
refrigerant
amount
Insufficient
refrigerant amount
Insufficient filling
Refer to P222, 36)Inspect Re-
frigerant Pressure (Inspect
Refrigerant Amount)
Refrigerant leakage
Blockage in the
refrigerant flow
path
Blockage in the strainer
Refer to P224, 44)Inspect
Strainer
Blocked indoor electronic expansion valve
Refer to P224, 42)Inspect for
Blockage in the Indoor Elec-
tronic Expansion Valve
Blockage in the check valve
Refer to P224, 45)Inspection
Check Valve (Refrigerant
Pressure Drop)
Sensor/Harness
system failure
Refrigerant low
pressure sensor
operation failure
Refrigerant low pressure
sensor failure
Refer to P224, 46)Inspect Re-
frigerant Low Pressure Sen-
sor
Contact failure / disconnec-
tion
Refrigerant high
pressure sensor
operation failure
Refrigerant high pressure
sensor failure
Refer to P223, 39)Inspect Re-
frigerant High Pressure Sen-
sor
Contact failure / disconnec-
tion
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