Specifications

SiUS39-601 Troubleshooting by Indication on the Remote Controller
Troubleshooting 137
2.15
“E4”
Outdoor Unit: Actuation of Low Pressure Sensor
Remote
Controller
Display
E4
Applicable
Models
RXYQ72M, 96M
Method of
Malfunction
Detection
Abnormality is detected by the pressure value with the low pressure sensor.
Malfunction
Decision
Conditions
Error is generated when the low pressure is dropped under specific pressure.
Supposed
Causes

Abnormal drop of low pressure (Lower than 21psi)

Defect of low pressure sensor

Defect of outdoor unit PC board

Stop valve is not opened.
Troubleshooting
(V2791)
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
Low pressure
at stop due to malfunction
is 21psi.
Measure
the voltage (VL)
of X45A pin No. (2) - (3)
of outdoor PC board (A2P).∗1
Is the relationship
between low
voltage and VL
normal?
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 PC board
(A1P).
NO
NO
YES
YES
Is stop valve opened?
Open stop valve.
NO
YES