Troubleshooting for Outdoor Unit Si18-525B
368 Troubleshooting
7.3 Actuation of Low Pressure Switch
Remote
Controller
Display
E4
Applicable
Models
AII outdoor unit models
Method of
Malfunction
Detection
Malfunction
Decision
Conditions
Error is generated when the low pressure is dropped under specific pressure.
Supposed
Causes
Abnormal drop of low pressure
Defect of low pressure sensor
Defect of outdoor unit PCB
Stop valve is not opened.
Troubleshooting
∗
1: Voltage measurement point
∗
2: Refer to pressure sensor, pressure / voltage characteristics table on P400.
(Q0423)
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
Is the malfunction
due to abnormal drop of low
pressure?
Measure
the voltage (VL)
of X45A pin No. (2) - (3)
of outdoor PCB (A1P).∗1
Is the relationship
between low
voltage and VL
normal?
∗2
Out of gas, refrigerant system
clogging, wiring and piping wrong
connection, stop valve closed,
electronic expantion valve fully
close malfunction.
Replace the low pressure sensor.
Replace outdoor unit PCB A1P.
NO
NO
YES
YES
Is stop valve opened? Open stop valve.
NO
YES
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