Daikin VRV-WIII RWEYQ72PTJU Service Manual page 253

SiUS30-1301
CHECK 5
Check for Causes of Wet Operation.
Referring to the Fault Tree Analysis (FTA) shown below, identify defective points.
[Cooling]
Indoor unit
electronic
expansion
valve opens
too much. (*1)
[Heating]
Wet operation
Condensing
unit electronic
expansion
valve opens too
much. (*2)
1: "Superheated degree control" in cooling is exercised with the indoor unit electronic expansion
Note:
2: "Superheated degree control" in heating is exercised with the condensing unit electronic
3: Guideline of superheated degree to judge as wet operation
Service Diagnosis
Refrigerant accumulation
Overcharge of refrigerant
Defective indoor
unit electronic
expansion valve
Defective
control
Defective control
of superheated
degree
Defective condensing
unit electronic
expansion valve
Defective
control
Dirty evaporator
Degraded
evaporating
capacity
Reduced
air quantity
valve.
expansion valve (EV1).
1 Suction gas superheated degree: Not more than 37.4°F; 2 Discharge gas superheated
degree: Not more than 59°F, 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.)
Troubleshooting by Indication on the 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 control PCB
Defective valve coil
Defective valve body
Defective power pressure sensor
Defective suction pipe thermistor
Defective control PCB
¬Does the heat exchanger get clogged?
Defective fan motor
Reduced
fan output
Defective control PCB
(including defective
capacity setting)
Increased
Dirty filter
resistance
in air
passage
Obstacles
¬Refer to information in the CHECK 6
section.
¬Does the valve coil have normal
resistance and insulation?
CHECK 11
(Refer to information in the
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?
CHECK 11
(Refer to information in the
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
¬Does the air filter get clogged?
¬Are there any obstacles in the air
passage?
245