Troubleshooting by Remote Controller
SiUS281117
Service Diagnosis
173
2.50 Check
Check for causes of rise in high pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the error points.
Note:
1: In cooling, it is normal if the outdoor unit electronic expansion valve (EV1) is fully open.
2: In heating, the indoor unit electronic expansion valve is used for “subcooling degree control”.
CHECK 1
Short circuit
Rise in high
pressure
Local
pressure
rise
High pipe
resistance
Stop valve closed
Bent or crashed pipe
Clogging of foreign
particles
←
Check to be sure the stop valve is open.
←
Conduct visual checks for pipe conditions.
←
Is there any temperature difference caused before
and after the filter or branch pipe.
←
Are the coil resistance and insulation normal?
[In cooling]
If the outdoor unit electronic
expansion valve is throttled:
(See
∗
1.)
Defective outdoor
unit electronic
expansion valve
Defective indoor
unit electronic
expansion valve
Defective valve coil
Defective valve body
A temperature difference in excess of 50
°
F between
the inlet and the outlet is deemed to be abnormal.
Defective
control
Defective high pressure sensor
Defective service monitor PCB
←
Are the electrical characteristics normal?
←
Is the pressure value checked with the Service Checker
corresponding to the measurement of the pressure sensor?
←
Are the coil resistance and insulation
normal?
Defective high
pressure
control
Defective valve coil
Defective valve body
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled:
(See
∗
2.)
Defective
control
Defective high pressure sensor
Defective indoor unit
liquid pipe thermistor
Defective service monitor PCB
←
Are the electrical characteristics normal?
←
In the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the pressure value checked with the Service
Checker corresponding to the measurement of the
pressure sensor?
[In cooling]
High suction
air
temperature
of the
condenser
[In heating]
High suction air
temperature of
outdoor unit
Short circuit
High outdoor air temperature
←
Is the suction air temperature not more than 115
°
F?
←
Is the outdoor air temperature not more than 115
°
F?
High suction
air temperature
of indoor unit
High outdoor air temperature
←
Is the suction air temperature not more than 81
°
F?
←
Is the indoor air temperature not more than 81
°
F?
Defective suction air thermistor of indoor unit
High suction air temperature of outdoor unit
Defective outdoor air temperature thermistor of outdoor unit
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the outdoor air temperature not more than 61˚FWB?
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Degradation
in condensing
capacity
Dirty condenser
Mixing of non-condensable gas
←
Is the heat exchanger clogged? (In cooling)
←
Is air or else mixed in the refrigerant system?
Decreased
fan airflow
rate
Decreased
fan
output
Defective fan
motor
←
Can the fan motor be rotated with hands?
Are the motor coil resistance and
insulation normal?
←
If a spare PCB is mounted, is the capacity
setting properly made?
←
Is the air filter clogged?
←
Is there any obstacle in the air passage?
Defective service
monitor PCB
(Including
capacity setting)
High air
passage
resistance
Dirty filter
Obstacle
Excessive refrigerant charging
Improper model selection [In heating]
←
Refer to troubleshooting "F6".
←
Is the indoor unit too small compared to
the large-sized outdoor unit?
