Check - Daikin VRV IV-S RXTQ-TAVJU Series Service Manual

SiUS331604E

4.57 Check

CHECK 1

Check for causes of rise in high pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
Rise in high
pressure
∗1: In cooling, it is normal if the outdoor unit electronic expansion valve is fully open.
Note:
∗2: In heating, the indoor unit electronic expansion valve is used for subcooling degree control.
Service Diagnosis
Local
High pipe
pressure
resistance
rise
[In cooling]
Defective outdoor
If the outdoor unit electronic
unit electronic
expansion valve is throttled:
expansion valve
(∗1.)
A temperature di f ference i n excess of 10°C (50˚F)
between the i n l e t and the outl e t i s deemed to be abnormal .
Defective
control
Defective
high pressure
Defective indoor
control
unit electronic
expansion valve
[In heating]
Defective
If the indoor unit electronic
control
expansion valve excessively
throttled:
(∗2.)
[In cooling]
High suction air
temperature of
High suction
outdoor unit
air
temperature
of the High suction
condenser air temperature
of indoor unit
Defective suction air thermistor of indoor unit
[In heating]
High suction air temperature of outdoor unit
Defective outdoor air temperature thermistor of outdoor unit
Degradation
Dirty condenser
in condensing
capacity
Mixing of non-condensable gas
Decreased
airflow rate
Excessive refrigerant charging
Improper model selection [In heating]
←Check to be sure the stop valve is open.
Stop valve closed
←Conduct visual checks for pipe conditions.
Bent or crashed pipe
←Is there any temperature difference caused before
Clogging of foreign
materials and after the filter or branch pipe.
←Are the coil resistance and insulation normal?
Defective valve coil
Defective valve body
←Is the pressure value checked with the Service Checker
Defective high pressure sensor
corresponding to the measurement value of the pressure sensor?
Defective main
←Are the voltage characteristics normal?
PCB
←Are the coil resistance and insulation
Defective valve coil
normal?
Defective valve body
←Is the pressure value checked with the Service
Defective high pressure sensor
Checker corresponding to the measurement value of
the pressure sensor?
Defective indoor unit
←In the connector properly connected?
liquid pipe thermistor
Are the thermistor resistance characteristics normal?
Defective main
←Are the voltage characteristics normal?
PCB
←Is the suction air temperature more than 43°C
Short circuit
(109°F)?
←Is the outdoor air temperature more than 43°C
High outdoor air
temperature
(109°F)?
←Is the suction air temperature more than 27°C
Short circuit
(80.6˚F)?
High room
←Is the room temperature more than 27°C (80.6˚F)?
temperature
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Is the outdoor air temperature more than 16°CWB
(60.8˚FWB)?
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Is the heat exchanger clogged? (In cooling)
←Is air or else mixed in the refrigerant system?
Defective fan
Decreased
motor
fan
Defective main
output
PCB (Including
capacity setting)
High
Dirty filter
airflow
passage
resistance
Obstacle
←Refer to
CHECK 6
←Is the indoor unit too small compared to
the large-sized outdoor unit?
Troubleshooting by Error Code
←Can the fan motor be rotated with hands?
Are the motor coil resistance and
insulation normal?
←If a spare PCB is installed, is the capacity
setting properly made?
←Is the air filter clogged?
←Is there any obstacle in the airflow passage?
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