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.
Faulty indoor
unit electronic
expansion valve
←Are the coil resistance and insulation
normal?
Faulty high
pressure
control
Faulty valve coil
Faulty valve body
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled:
(See *1.)
Faulty
control
Faulty high pressure sensor
Faulty indoor unit
liquid pipe thermistor
Faulty control 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?
High suction
air
temperature
of the
condenser
[In heating]
High suction air
temperature of
indoor unit
High ambient temperature
←
Is the suction air temperature not more than 27°C?
←
Is the indoor temperature not more than 27°C?
Faulty suction air thermistor of indoor unit
High suction air temperature of outdoor unit
Faulty outdoor temperature thermistor of outdoor unit
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the outdoor temperature not more than 16°CWB?
←
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
Faulty fan
motor
←Can the fan motor be rotated with hands?
Are the motor coil resistance and insulation
normal?
←If a spare PC board is mounted, is the
capacity setting properly made?
Faulty control
PC board
(Including
capacity setting)
High air
passage
resistance
Dirty filter
←Is the air filter clogged?
Obstacle
←Is there any obstacle in the air passage?
Excessive refrigerant charging
Improper model selection
[In heating]
←Refer to P.173.
←Is the indoor unit too small compared to
the large-sized outdoor unit?
*1: In heating, the indoor unit electronic expansion valve is used for “subcooled degree control”.
(For details, refer to “Electronic Expansion Valve Control” on P.72.)
C: SDK04009
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