Superheat Operation Check - Daikin RXQ12AHR Service Manual

SiAF341904E
6.3

Superheat Operation Check

CHECK 3 Identify the defective points referring to the failure factor analysis (FTA) as follows.
Defective
discharge
pipe
temperature
control
Temperature
increase of
discharge
pipe
Compressor
overheat
If the indoor unit
electronic
expansion valve is
excessively
throttled. ( 1)
Defective
superheated
degree
control.
Refrigerant
shortage
Large resistance
of piping
Note(s)
1. "Superheating temperature control" in cooling mode is conducted by indoor unit electronic
expansion valve.
2. Judgment criteria of superheat operation:
(1) Suction gas superheating temperature: 10 degrees and over.
(2) Discharge gas superheating temperature: 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.)
Reference
CHECK 7 Refer to page 293.
Reference
CHECK 8 Refer to page 294.
Part 6 Service Diagnosis
Hot gas circuit clogging
Defective hot
Defective solenoid
gas bypass
valve coil
control
Defective solenoid
valve body
Defective outdoor unit main PCB
Subcooling
electronic
expansion
valve failure
Defective
subcooling
electronic
expansion valve Control
failure
control (Y2E)
Superheat due to
shaft damage
Superheat due to
defective compressor
Indoor unit
Defective valve coil
electronic
expansion
Defective valve body
valve failure
Irregular piping length
Bend/collapse
(Including moisture choke)
Stop valve is closed.
m Check if coil resistance and insulation
are normal.
Defective valve coil
m Check if coil resistance and
insulation are normal.
Defective valve
body
m Check if the pressure value given by the
Defective low
pressure sensor service checker corresponding to actual
measurement value by the sensor.
Defective subcooling
m Check if the connector is connected properly.
heat exchanger outlet
Check if the thermistor resistance property is
thermistor
normal.
Defective outdoor
m Check if the voltage property is
unit main PCB
normal.
m Check if coil resistance and insulation are
normal.
m Refer to CHECK 7
m Does the piping length fall in the permissible range?
m Conduct visual checks.
m Remove the moisture by vacuum break. (Refer to CHECK 8)
m Check if the stop valve is open.
Check
289