Daikin VRV - WII Service Manual page 264

SiUS30-604
[CHECK 3] Check for causes of overheat operation
Referring to the Fault Tree Analysis (FTA) shown below, identify the faulty points.
Faulty
discharge
pipe
temperature
control
Rise in
discharge
pipe
temperature
Superheated
compressor
[In cooling]
If the indoor unit
electronic
expansion valve
excessively
throttled
(∗3)
Faulty
superheated
degree
control
[In heating]
If the outside unit
electronic
expansion valve
excessively
throttled
(∗4)
Inadequate refrigerant
quantity
High pipe resistance
∗1 : For hot gas bypass control, refer to "Low Pressure Protection Control" on page 71.
∗2 : For subcooling electronic expansion valve, refer to page 67.
∗3 : In cooling, the indoor unit electronic expansion valve is used for "superheated degree control". (Refer to page 89.)
∗4 : In heating, the outside unit electronic expansion valve (Y1E) is used for "superheated degree control." (Refer to page 67.)
∗5 : Reference values for superheated degree to be used in the judgment of overheat operation
Suction gas superheated degree: 50°F or more
when it is immediately after startup, under drop control or other specific conditions.
(The values above must be used only for reference purposes. Even it is operated within the range above,operation
may be normal in other conditions.)
Troubleshooting
Clogged hot gas passage
Faulty hot
Faulty solenoid valve coil
gas bypass
control
Faulty solenoid valve body
(∗1)
Faulty control PCB
Faulty
subcooling
[In cooling only]
electronic
expansion valve
Faulty subcooling
electronic
expansion valve
Faulty
(Y3E) control
control
(∗2)
Four-way changeover valve is
Faulty four-way located in an intermediate position
changeover
valve function
Leakage from hot gas bypass valve
Superheat caused by
axis damage
Superheat caused by
faulty compressor
Faulty valve coil
Faulty indoor unit
electronic
expansion valve
Faulty valve body
Faulty gas pipe
thermistor of indoor unit
Faulty control
Faulty liquid pipe
thermistor of indoor unit
Faulty control PCB
Faulty valve coil
Faulty outside
unit electronic
expansion valve
Faulty valve body
Faulty low pressure sensor
Faulty control
Faulty suction pipe thermistor
Faulty control PCB
Abnormal pipe length
Bent or Crush of pipe
(Including moisture choke)
Stop valve closed
Discharge gas superheated degree: 113°F or more, excluding
Troubleshooting (OP: Unified ON/OFF Controller)
← Are the coil resistance and insulation normal?
← Are the coil resistance and insulation
Faulty valve coil
normal?
Faulty valve body
← Are the voltage characteristics normal?
Faulty low pressure sensor
Faulty subcooling heat
← Is the connector properly connected?
exchanger outlet thermistor
Are the thermistor resistance
characteristics normal?
← Does the pressure value of the Service
Faulty control PCB
Checker match the reading of the
pressure sensor?
← Is the temperature of piping connected to the
four-way changeover valve normal?
← 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?
← Are the coil resistance and insulation normal?
← Are the voltage characteristics normal?
← Is the connector properly connected?
Are the thermistor resistance characteristics
normal?
← Does the pressure value of the Service Checker
match the reading of the pressure sensor?
← Refer to [CHECK 6] on page 254.
← Is the piping length in the permissible range?
← Conduct visual checks for pipe conditions.
← Eliminate moisture by vacuum break.
← Check to be sure the stop valve is open.
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