SiUS281117
Troubleshooting by Remote Controller
180
Service Diagnosis
Check for causes of wet operation.
Referring to the Fault Tree Analysis (FTA) shown below, identify defective points.
CHECK 7
Refrigerant accumulation
Overcharge of refrigerant
Defective crankcase heater
Frequent ON/OFF of compressor
[Cooling]
Indoor unit
electronic
expansion
valve opens too
much. (
∗
1)
[Heating]
Outdoor unit
electronic
expansion
valve opens too
much. (
∗
2)
Defective control
of superheated
degree
Defective
indoor unit
electronic
expansion
valve
Defective
outdoor unit
electronic
expansion
valve
Defective
control
Defective
control
Defective valve coil
Defective service monitor PCB
Defective valve body
Defective valve coil
Defective valve body
Defective power pressure sensor
Defective suction pipe thermistor
Defective service monitor PCB
←
Does the valve coil have normal
resistance and insulation?
←
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?
←
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?
Wet operation
Degraded
evaporating
capacity
Increased
resistance
in air
passage
Dirty evaporator
Reduced
air quantity
Reduced
fan output
∗
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 outdoor unit electronic expansion valve
(EV1).
∗
3: Guideline of superheated degree to judge as wet operation
Suction gas superheated degree: Not more than 37.4
°
F;
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.)
Defective fan motor
Dirty filter
Obstacles
←
Does the heat exchanger get clogged?
Defective service monitor PCB
(including defective capacity
setting)
Defective indoor unit
gas pipe thermistor
Defective indoor unit
liquid pipe thermistor
