Daikin VRV S RXQ4/5ARV1, Service Manual

Page: 344 / 377

Check SiAF332111E
338 Part 6 Service Diagnosis
Reference
Reference
6.2 Low Pressure Check
CHECK 2
Referring to the Fault Tree Analysis (FTA) shown below, probe the defective points.
CHECK 7 Refer to page 346.
CHECK 8 Refer to page 347.
Abnormally low
pressure
(Low evaporating
temperature)
Defective
low pressure
control
Defective
compressor
capacity
control
Defective low pressure sensor
Are the voltage characteristics normal? Defective outdoor unit main PCB
Is the pressure value checked with the Service Checker
corresponding to the measurement of the pressure sensor?
Defective
low pressure
protection
control
Defective low pressure sensor
Are the voltage characteristics normal?
Defective hot gas solenoid valve
Are the coil resistance and insulation normal?
Defective outdoor unit main PCB
Is the pressure value checked with the Service Checker
corresponding to the measurement of the pressure sensor?
In cooling
If the indoor unit
electronic
expansion valve is
throttled too much:
Defective indoor
unit electronic
expansion valve
Defective valve coil
Defective valve body
Are the coil resistance and insulation normal?
Defective
control
Defective gas pipe
thermistor of indoor unit
Defective liquid pipe
thermistor of indoor unit
Defective outdoor unit main PCB
Check for the thermistor resistance and connection.
Check for the thermistor resistance and connection.
Are the voltage characteristics normal?
Low suction
air temperature
of the
evaporator
Low suction air
temperature of
indoor unit
Short circuit
Is the suction air temperature more than 14°C?
Is the indoor temperature less than 14°C?
Low room temperature
Defective suction air thermistor of indoor unit
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
High pipe
resistance
Abnormal piping length
Bent or crushed pipe
Clogging of foreign particles
Stop valve closed
Does the piping length fall in the permissible range?
Conduct visual checks for pipe conditions.
Is there any temperature difference caused before
and after the filter or branch pipe?
Check to be sure the stop valve is open.
Less
circulation
quantity of
refrigerant
Degradation
in condensing
capacity
Refrigerant shortage
Moisture choke
Eliminate moisture by vacuum operation. (
Refer to CHECK 8 .)
Dirty
evaporator
Decreased
fan airflow
rate
Decreased
fan output
Defective fan motor
Can the fan motor be rotated with hands?
Are the motor coil resistance and insulation normal?
Is the heat exchanger clogged?
Defective outdoor unit
main PCB (Including
capacity setting)
If a spare PCB is mounted, is the capacity
setting properly made?
High airflow
passage
resistance
Dirty filter
Is there any obstacle in the air passage?
Is the air filter clogged?
Obstacle
Defective electronic
expansion valve
control
Refer to CHECK 7 .