Service manual

SiUS28-902_a Troubleshooting by Indication on the Remote Controller
Troubleshooting 130
Troubleshooting
∗2: Voltage measurement point
∗1: Refer to Thermistor Resistance / Temperature Characteristics table on P.166.
∗2: Refer to Pressure Sensor, Pressure / Voltage Characteristics table on P.168.
The suction
pipe1 temp. minus
low pressure saturation
temp. is 36 °F
or higher.
Resistance
is normal when
measured with the
thermistor (R3T) for
suction pipe1 disconnected
from the outdoor
unit P.C.B.
*1
Out of gas or refrigerant
system is clogged. Requires
check of refrigerant system.
Replace the thermistor.
Replace the outdoor unit
P.C.B. (A1P).
YES
YES
NO
NO
Out of gas, closing of stop
valve or refrigerant system is
clogged. Requires check of
refrigerant system.
Replace the main outdoor
unit P.C.B. (A1P).
Replace the low pressure
sensor.
YES
YES
Is the
low pressure sensor
correct?
Replace the low pressure
sensor.
NO
NO
Cooling
Low pressu
re
is 36psi
or less.
The
voltage
of X18A pins (2)
and (3) on main
outdoor unit P.C.B.
(A1P) is 1.0 VDC or less.
(Low pressure
sensor output
voltage)
*2
NO
NO
YES
YES
Caution
Be sure to turn off the power switch before connecting or disconnecting
the connector, or parts could be damaged.