Daikin VRVIII-S, Service Manual

Page: 204 / 266

SiENBE34-703 Troubleshooting by Indication on the Unified ON/OFF Control
Troubleshooting 193
[CHECK 1] Check for causes of rise in high pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the faulty points.
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.
[In cooling]
If the outdoor unit electronic
expansion valve is throttled:
(See *1.)
Faulty outdoor
unit electronic
expansion valve
Faulty indoor
unit electronic
expansion valve
Faulty valve coil
Faulty valve body
Are the coil resistance and insulation normal?
Faulty
control
Faulty high pressure sensor
Faulty control 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?
Faulty high
pressure
control
Faulty valve coil
Faulty valve body
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled: (See *2.)
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?
[In cooling]
High suction
air
temperature
of the
condenser
[In heating]
High suction air
temperature of
outdoor unit
Short circuit
High ambient temperature
Is the suction air temperature not more than
46°C?
Is the outdoor temperature not more than 46°C?
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 page 313.
Is the indoor unit too small compared to
the large-sized outdoor unit?
*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”.
C: SDK04009
A temperature difference in excess of 10°C between
the inlet and the outlet is deemed to be abnormal.