Daikin LRYEQ16AY1 Service Manual page 289

SiBE811001EB
CHECK 3-1
Check the Factors of Overheat Operation (Air conditioning)
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
[In cooling mode]
If the indoor unit
electronic
expansion valve
is excessively
throttled. (∗2)
Defective
superheated
degree
control.
[In heading mode]
If the outdoor unit
electronic
expansion valve
is excessively
throttled. (∗3)
Refrigerant shortage
Large resistance
of piping
∗1: Refer to subcooling electronic expansion valve control.
∗2: "Superheating temperature control" in cooling mode is conducted by indoor unit electronic expansion valve.
∗3: Superheating temperature control in heating mode is conducted by outdoor unit electronic expansion valve (Y1E).
∗4: Judgement criteria of superheat operation:
(1) Suction gas superheating temperature: 20 degrees and over. (2) Discharge gas superheating temperature: 110 degrees and
over, except for immediately after starting and drooping 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.)
CONVENI-PACK
Subcooling
electronic
expansion
valve failure
Defective electronic
expansion valve
control (Y2E)
Control
failure
(∗1)
Defective of
Four way valve (A or B or C)
four way valve
is in the middle position.
operation
Superheat due to
shaft damage
Superheat due to
defective compressor
Defective valve coil
Indoor unit
electronic expansion
valve failure
Defective valve body
Defective thermistor for
indoor unit gas pipe
Defective control
Defective thermistor for
indoor unit liquid pipe
Defective control PCB
Defective valve coil
Outdoor unit
electronic expansion
valve failure
Defective valve body
Defective low
pressure sensor
Defective thermistor
Defective control
for suction pipe
Defective control PCB
Irregular piping length
Bend/collapse
(Including moisture choke)
Stop valve is closed.
← Check if coil resistance and
Defective valve coil
insulation are normal.
Defective valve body
Defective low
← Check if the voltage
pressure sensor
property is normal.
← Check if the connector is
Defective subcooling
connected properly.
heat exchanger outlet
Check if the thermistor
thermistor
resistance property is normal.
← Check if the pressure value
Defective control PCB
given by the service checker
corresponding to actual
measurement value by the
sensor.
← Check if the piping temperature
connected to the four way valve is
normal.
← Check if coil resistance and
insulation are normal.
← Check if the connector is connected
properly.
Check if the thermistor resistance
property is normal.
← Check if the connector is connected
properly.
Check if the thermistor resistance
property is 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.
← Check if the stop valve is open.
Troubleshooting
288