Check SiAF332111E
344 Part 6 Service Diagnosis
6.5 Wet Operation Check
CHECK 5 Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
1: Superheating temperature control in cooling is conducted by indoor unit electronic
expansion valve.
2: Guideline of superheating degree to judge as wet operation
(1) Suction gas superheating degree: Less than 3°C;
(2) Discharge gas superheating degree: Less than 15°C,
except immediately after compressor starts up or is running under dropping control.
(Use the above values as a guide. Depending on the other conditions, the unit may be normal
despite the values within the above range.)
CHECK 6 Refer to page 345.
Refrigerant stagnation
Overcharge of refrigerant
Defective crankcase heater
Frequent ON/OFF of compressor
[In cooling]
Indoor unit
electronic
expansion
valve opens too
much. (∗1)
Defective control
of superheating
degree
Defective
indoor unit
electronic
expansion
valve
Defective
control
Defective valve coil
Defective main PCB
Defective valve body
←Refer to CHECK 6 .
←
Are the coil resistance and
insulation normal?
←Is the connector properly connected?
Are the thermistor resistance
characteristics normal?
←Is the connector properly connected?
Are the thermistor resistance
characteristics normal?
←Can the fan motor be rotated
with hands?
Are the motor coil resistance and
insulation normal?
←Is the air filter clogged?
←Is there any obstacle in the
airflow passage?
Wet operation
Degraded
evaporating
capacity
High
airflow
passage
resistance
Dirty evaporator
Decreased
airflow rate
Decreased
fan output
Defective fan motor
Dirty filter
Obstacles
←Does the heat exchanger get clogged?
Defective main PCB
(including capacity
setting)
Defective gas pipe
thermistor of indoor unit
Defective liquid pipe
thermistor of indoor unit
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