Daikin FCQ18PVJU Service Manual page 163

SiUS28-902_a
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
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled:
(See *2.)
[In cooling]
High suction
air
temperature
of the
condenser
[In heating]
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
Troubleshooting by Indication on the Unified ON/OFF Controller
Stop valve closed
High pipe
Bent or crashed pipe
resistance
Clogging of foreign
Faulty outdoor
Faulty valve coil
unit electronic
expansion valve
Faulty valve body
A
temperature difference in excess of 50°F
between the inlet and the outlet is deemed abnormal.
Faulty high pressure sensor
Faulty
control
Faulty control P.C.B.
Faulty valve coil
Faulty indoor
unit electronic
expansion valve
Faulty valve body
Faulty high pressure sensor
Faulty indoor unit
Faulty
liquid pipe thermistor
control
Faulty control P.C.B.
Short circuit
High suction air
temperature
of outdoor unit High ambient temperature
Short circuit
High suction
air temperature
High ambient temperature
Faulty suction air thermistor of indoor unit
High suction air temperature of outdoor unit
Faulty outdoor temperature thermistor of outdoor unit
Dirty condenser
Mixing of non-condensable gas
Decreased
fan
Decreased
output
fan airflow
rate
High air
passage
resistance
¬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
115°F?
¬Is the outdoor temperature not more than 115°F?
¬Is the suction air temperature not more than 81°F?
¬Is the indoor temperature not more than 81°F?
¬Is the connector properly connected?
Are the thermistor resistance characteristics normal?
¬Is the outdoor temperature not more than 61°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
¬Can the fan motor be rotated with hands?
motor
Are the motor coil resistance and
insulation normal?
Faulty control
P.C.B. ¬If a spare P.C.B. is mounted, is the capacity
(Including
setting properly made?
capacity setting)
¬Is the air filter clogged?
Dirty filter
¬Is there any obstacle in the air passage?
Obstacle
¬Refer to P.112.
¬Is the indoor unit too small compared to
the large-sized outdoor unit?
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