Daikin VRVIII-S Service Manual page 204

SiENBE34-703
[CHECK 1] Check for causes of rise in high pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the faulty points.
Local
pressure
rise
[In cooling]
If the outdoor unit electronic
expansion valve is throttled:
(See *1.)
Rise in high
pressure
Faulty high
pressure
control
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled: (See *2.)
[In cooling]
High suction
air
temperature
of the
condenser
Degradation
in condensing
capacity
Excessive refrigerant charging
Improper model selection [In heating]
*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 "subcooled degree control".
Troubleshooting
High pipe
resistance
Faulty outdoor
unit electronic
expansion valve
A temperature difference in excess of 10°C between
the inlet and the outlet is deemed to be abnormal.
Faulty
control
Faulty indoor
unit electronic
expansion valve
Faulty
control
High suction air
temperature of
outdoor unit
High suction
air temperature
of indoor unit
Faulty suction air thermistor of indoor unit
[In heating]
High suction air temperature of outdoor unit
Faulty outdoor temperature thermistor of outdoor unit
Dirty condenser
Mixing of non-condensable gas
Decreased
fan airflow
rate
Troubleshooting by Indication on the Unified ON/OFF Control
Stop valve closed
Bent or crashed pipe
Clogging of foreign
particles
Faulty valve coil
Faulty valve body
Faulty high pressure sensor
Faulty control PCB
Faulty valve coil
Faulty valve body
Faulty high pressure sensor
Faulty indoor unit
liquid pipe thermistor
Faulty control PCB
Short circuit
High ambient temperature
Short circuit
High ambient temperature
Is the heat exchanger clogged? (In cooling)
Is air or else mixed in the refrigerant system?
Faulty fan
Decreased
motor
fan
output
Faulty control
PC board
(Including
capacity setting)
Dirty filter
High air
passage
resistance
Obstacle
Refer to page 313.
Is the indoor unit too small compared to
the large-sized outdoor unit?
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?
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?
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?
Is the suction air temperature not more than
46°C?
Is the outdoor temperature not more than 46°C?
Is the suction air temperature not more than 27°C?
Is the indoor temperature not more than 27°C?
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?
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?
Is the air filter clogged?
Is there any obstacle in the air passage?
C: SDK04009
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