Daikin VRV S RXQ4/5ARV1, Service Manual

Page: 345 / 377

SiAF332111E Check
Part 6 Service Diagnosis 339
Note(s)
Reference
Reference
6.3 Superheat Operation Check
CHECK 3
Identify the defective points referring to the failure factor analysis (FTA) as follows.

1. “Superheating degree control” in cooling mode is conducted by indoor unit electronic
expansion valve.

2. Judgment criteria of superheat operation:
(1) Suction gas superheating degree: 10 degrees and over.
(2) Discharge gas superheating degree: 45 degrees and over, except for immediately after
starting and dropping control, etc.
(Use the above stated values as a guide. Depending on the other conditions, the unit may be
normal despite the values within the above scope.)
CHECK 7 Refer to page 346.
CHECK 8 Refer to page 347.
Temperature
increase of
discharge
pipe
Defective
discharge
pipe
temperature
control
Compressor
overheat
Defective
superheating
degree
control.
Refrigerant
shortage
Large resistance
of piping
Defective hot
gas bypass
control
Defective
subcooling
electronic
expansion valve
control (Y2E)
Superheat due to
shaft damage
Superheat due to
defective compressor
Irregular piping length
Bend/collapse
(Including moisture choke)
Stop valve is closed.
Hot gas circuit clogging
Defective solenoid
valve coil
Defective solenoid
valve body
Defective outdoor unit main PCB
Subcooling
electronic
expansion
valve failure
Control
failure
Defective valve coil
Defective valve
body
Defective low
pressure sensor
Defective subcooling
heat exchanger outlet
thermistor
Defective outdoor
unit main PCB
Check if coil resistance and insulation
are normal.
Check if coil resistance and
insulation are normal.
Check if the voltage property is
normal.
Check if the connector is connected properly.
Check if the thermistor resistance property is
normal.
Check if the pressure value given by the
service checker corresponding to actual
measurement value by the sensor.
Does the piping length fall in the permissible range?
Conduct visual checks.
Remove the moisture by vacuum break. (Refer to CHECK 8 )
Check if the stop valve is open.
If the indoor unit
electronic
expansion valve is
excessively
throttled. (
1)
Refer to
CHECK 7
Defective valve coil
Defective valve body
Defective indoor
unit electronic
expansion valve
Defective
control
Defective indoor
gas pipe thermistor
Defective indoor
liquid pipe thermistor
Defective main
PCB
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Are the coil resistance and insulation normal?
Is the connector properly connected?
Are the thermistor resistance characteristics normal?