Daikin RXYQ96PYDN Service Manual page 477

Troubleshooting (OP: Unified ON/OFF Controller)
[CHECK 5] Check for causes of rise in high pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the faulty points.
Rise in high
pressure
*1: In cooling, it is normal if the outdoor unit electronic expansion valve (EVM) is fully open.
*2: In heating, the indoor unit electronic expansion valve is used for "subcooled degree control".
462
Local
High pipe
pressure
resistance
rise
[In cooling]
Faulty outdoor
If the outdoor unit electronic
unit motorized
expansion valve is throttled:
valve
(See *1.)
A temperature di f ference i n excess of 50°F
between the i n l e t and the outl e t i s deemed to be abnormal .
Faulty
control
Faulty high
pressure
Faulty indoor
control
unit motorized
valve
[In heating]
Faulty
If the indoor unit electronic
control
expansion valve excessively
throttled:
(See *2.)
[In cooling]
High suction air
temperature
High suction
of outdoor unit
air
temperature
High suction
of the
condenser 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
Degradation
Dirty condenser
in condensing
capacity
Mixing of non-condensable gas
Decreased
fan airflow
rate
Excessive refrigerant charging
Improper model selection [In heating]
←Check to be sure the stop valve is open.
Stop valve closed
←Conduct visual checks for pipe conditions.
Bent or crashed pipe
←Is there any temperature difference caused before
Clogging of foreign
particles and after the filter or branch pipe.
←Are the coil resistance and insulation normal?
Faulty valve coil
Faulty valve body
←Are the electrical characteristics normal?
Faulty high pressure sensor
←Is the pressure value checked with the Service Checker
Faulty control PC board
corresponding to the measurement of the pressure sensor?
←Are the coil resistance and insulation
Faulty valve coil
normal?
Faulty valve body
←Are the electrical characteristics normal?
Faulty high pressure sensor
←In the connector properly connected?
Faulty indoor unit
Are the thermistor resistance characteristics normal?
liquid pipe thermistor
←Is the pressure value checked with the Service
Faulty control PC board
Checker corresponding to the measurement of the
pressure sensor?
←Is the suction air temperature not more than
Short circuit
109.4°F?
←Is the outdoor temperature not more than
High ambient temperature
109.4°F?
←Is the suction air temperature not more than 80.6°F?
Short circuit
←Is the indoor temperature not more than 80.6°F?
High ambient temperature
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Is the outdoor temperature not more than 60.8°FWB?
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Is the heat exchanger clogged? (In cooling)
←Is air or else mixed in the refrigerant system?
Faulty fan
Decreased
motor
fan
Faulty control
output
PC board
(Including
capacity setting)
Dirty filter
High air
passage
resistance
Obstacle
←Refer to P376.
←Is the indoor unit too small compared to
the large-sized outdoor unit?
SiUS34-801A_b
←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?
SDK04009
Troubleshooting