Troubleshooting
SiENBE28-901
134
Air Cooled Refrigeration Condensing Unit
[Check 5] Check for Causes of Wet Operation
Referring to the Fault Tree Analysis (FTA) shown below, identify faulty points.
Refrigerant
accumulation
[In cooling]
If the indoor unit
electronic
expansion
valve excessively
opens: (See
∗
1)
←
See [Check 6].
∗
1. The indoor unit electronic expansion valve exerts "superheated degree control" in cooling.
∗
2. The outdoor unit electronic expansion valve (EV1) exerts "superheated degree control" in defrosting.
∗
3. Guideline for superheated degree by which a malfunction is judged as wet operation
(1) Suction gas superheated degree: Less than 3°C / (2) Discharge gas superheated degree: Less than 15°C; provided,
however, that superheated degrees immediately after startup or for drooping control are excluded.
(The values aforementioned are just a guideline. Even if the values fall within the range shown above, these values may be normal
depending on other conditions.)
Excessive compressor
ON-OFF
Refrigerant overcharge
Faulty
superheated
degree control
Faulty indoor
unit electronic
expansion valve
Faulty
control
Faulty outdoor
unit electronic
expansion valve
Faulty
control
Wet
operation
[In defrosting]
If the outdoor unit
electronic
expansion valve
excessively
opens: (See
∗
2)
Dirty
evaporator
Drop in
air
volume
Degradation in
evaporating
capacity
Faulty valve coil
Faulty valve body
Faulty indoor unit gas
pipe thermistor
Faulty indoor unit
liquid pipe thermistor
Faulty outdoor unit
main PCB
Faulty valve coil
Faulty valve body
Faulty low pressure
sensor
Faulty suction pipe
thermistor
Faulty outdoor unit
main PCB
Drop in
fan
output
High air
duct
resistance
Faulty fan motor
Faulty outdoor unit
main PCB (including
capacity setting)
Dirty filter
Obstacles
←
Is the coil resistance and the
insulation normal?
←
Is the connector properly
connected?
Are the thermistor resistance
characteristics normal?
←
Is the connector properly
connected?
Are the thermistor resistance
characteristics normal?
←
Is the coil resistance and the
insulation normal?
←
Are the voltage characteristics normal?
Is the connector properly connected?
←
Are the thermistor resistance
characteristics normal?
←
Is the pressure value on the
Service Checker matched to the
measurement of sensor?
←
Can the fan motor be rotated by hand?
Is the resistance and insulation of
motor coil normal?
←
Does the heat exchanger get clogged?
←
Does the air filter get clogged?
←
Is there any obstacle in the air
duct?