Superheat Operation Check - Daikin SkyAir RZR-TA Series Service Manual

Check
5.3

Superheat Operation Check

CHECK 3
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
Temperature
increase of
discharge
pipe
Note(s)
∗1: Refer to Low pressure protection control on page 118.
∗2: Refer to Subcooling electronic expansion valve control on page 108.
∗3: Superheating temperature control in cooling is conducted by indoor unit electronic
∗4: Superheating temperature control in heating is conducted by outdoor unit electronic
∗5: Judgment criteria of superheat operation: (1) Suction gas superheated degree: 10°C
294
Defective hot
gas bypass
control
(*1)
Defective
[In cooling only]
discharge
pipe Defective
temperature subcooling
control electronic
expansion
valve control
(*2)
Defective four
way valve
operation
Superheat due to
shaft damage
Compressor
overheat
Superheat due to
defective compressor
Defective indoor
unit electronic
expansion valve
[In cooling]
If the indoor unit
electronic
expansion valve is
throttled too much:
Defective
(*3)
control
Defective
superheated
degree
control.
Defective
outdoor unit
electronic
expansion valve
[In heating]
If the outdoor unit
electronic
Defective
expansion valve
control
excessively
throttled: (*4)
Refrigerant
shortage
Abnormal piping length
Bent or crushed pipe
High pipe
(Including moisture choke)
resistance
Stop valve closed.
expansion valve.
expansion valve.
(18°F) and over. (2) Discharge gas superheated degree: 45°C (81°F) and over, 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.)
Hot gas circuit clogging
Defective solenoid
←Are the coil resistance and insulation normal?
valve coil
Defective solenoid
valve body
Defective service
monitor PCB
Defective valve coil
Defective
subcooling
Defective valve
electronic
body
expansion
valve Defective low
pressure sensor
Defective subcooling
Defective
heat exchanger outlet
control
thermistor
Defective 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 gas pipe
←Is the connector properly connected?
thermistor of indoor unit
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 main
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 main
←Are the voltage characteristics normal?
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.
SiUS281811EA
←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?
Part 6 Service Diagnosis