Superheat Operation Check - Daikin VRV Aurora RXLQ-TATJU Series Service Manual

SiUS341802EC
4.3

Superheat Operation Check

CHECK 3
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points
Defective
discharge
pipe
temperature
control
Temperature
increase of
discharge
pipe
Compressor
overheat
[In cooling]
If the indoor unit
electronic
expansion valve is
throttled too much:
(2)
Defective
superheating
degree
control.
[In heating]
If the outdoor unit
electronic
expansion valve
excessively
throttled: (3)
Refrigerant
shortage
High pipe
resistance
Note(s)
1. Refer to Low pressure protection control for hot gas bypass control.
2. Superheating temperature control in cooling is conducted by indoor unit electronic expansion
3. Superheating temperature control in heating is conducted by outdoor unit electronic
Part 6 Service Diagnosis
Defective hot
gas bypass
control
(1)
[In cooling only]
Defective
injection
electronic
expansion Defective
valve control control
Defective four
way valve
operation
Superheat due to
shaft damage
Superheat due to
defective compressor
Defective indoor
unit electronic
expansion valve
Defective
control
Defective
outdoor unit
electronic
expansion valve
Defective
control
Abnormal piping length
Bent or crashed pipe
(Including moisture choke)
Stop valve closed.
valve.
expansion valve (main).
Hot gas circuit clogging
Defective solenoid
Are the coil resistance and insulation normal?
valve coil
Defective solenoid
valve body
Defective outdoor unit
main PCB
Defective valve coil
Defective
injection
Defective valve
electronic
body
expansion
valve
Defective low
pressure sensor
Defective subcooling
heat exchanger outlet
thermistor
Defective outdoor
unit main PCB
Four way valve is in the
Check if the piping temperature connected
middle position.
to the four way valve is normal.
Leak from hot gas bypass
valve
Defective valve coil
Are the coil resistance and insulation normal?
Defective valve body
Defective thermistor for
Is the connector properly connected?
indoor unit gas pipe
Are the thermistor resistance characteristics normal?
Defective thermistor for
Is the connector properly connected?
indoor unit liquid pipe
Are the thermistor resistance characteristics normal?
Defective indoor
unit control PCB
Defective valve coil Are the coil resistance and insulation normal?
Defective valve body
Is the pressure value checked with the Service
Defective low pressure
Checker corresponding to the measurement
sensor
value of the pressure sensor?
Defective suction pipe
Is the connector properly connected?
thermistor
Are the thermistor resistance characteristics normal?
Defective outdoor
Are the voltage characteristics normal?
unit main PCB
Refer to CHECK 7 .
Does the piping length fall in the permissible range?
Conduct visual checks.
Eliminate moisture by vacuum operation. (Refer to CHECK 8 .)
Check if the stop valve is open.
Are the coil resistance and
insulation normal?
Is the pressure value checked with the
Service Checker corresponding to the
measurement value of the pressure sensor?
Is the connector properly connected?
Are the thermistor resistance characteristics
normal?
Are the voltage characteristics normal?
Check
370