Daikin VRV II-Q RQYQ8-48PY1B Service Manual page 193

SiBE341027
CHECK 5
Check for causes of wet operation.
Referring to the Fault Tree Analysis (FTA) shown below, identify defective points.
Refrigerant accumulation
Overcharge of refrigerant
[Cooling]
Indoor unit
electronic
expansion
valve opens
too much. (∗1)
Defective control
of superheated
degree
[Heating]
Wet operation
Outside unit
electronic
expansion
valve opens too
much. (∗2)
Degraded
evaporating
capacity
∗1: "Superheated degree control" in cooling operation is exercised with the indoor unit electronic expansion valve.
∗2: "Superheated degree control" in heating operation is exercised with the outside unit electronic expansion valve
(EV1).
∗3: Guideline of superheated degree to judge as wet operation
15°C, except immediately after compressor starts up or is running under drooping control.
(Use the values shown above as a guideline. Even if the superheated degree falls in the range, the compressor
may be normal depending on other conditions.)
Service Diagnosis
Defective indoor
unit electronic
expansion valve
Defective
control
Defective outside
unit electronic
expansion valve
Defective
control
Dirty evaporator
Reduced
air quantity
Suction gas superheated degree: Not more than 3°C;
Troubleshooting by Remote Controller
Defective crankcase heater
Frequent ON/OFF of compressor
Defective valve coil
Defective valve body
Defective indoor unit
gas pipe thermistor
Defective indoor unit
liquid pipe thermistor
Defective service monitor PCB
Defective valve coil
Defective valve body
Defective power pressure sensor
Defective suction pipe thermistor
Defective service monitor PCB
←Does the heat exchanger get clogged?
Defective fan motor
Reduced
fan output
Defective service monitor PCB
(including defective capacity
setting)
Increased
Dirty filter
resistance
in air
passage
Obstacles
Discharge gas superheated degree: Not more than
←Refer to information in the
CHECK 6
section.
←Does the valve coil have normal
resistance and insulation?
(Refer to information in the
CHECK 11
section.)
←Is the connector correctly connected?
Are the thermistor resistance
characteristics normal?
←Is the connector correctly connected?
Are the thermistor resistance
characteristics normal?
←Does the valve coil have normal
resistance and insulation?
(Refer to information in the
CHECK 11
section.)
←Are the voltage characteristics normal?
←Is the connector correctly connected?
Does the thermistor have normal
resistance characteristics?
←Is the pressure reading of the service
checker corresponding to the actual
measurement of the sensor?
←Can the fan motor be rotated by
hand?
Does the fan motor coil have
normal resistance and
insulation?
←Does the air filter get clogged?
←Are there any obstacles in the air
passage?
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