Daikin SkyAir RZR-P Series Service Manual page 181

SiUS281117
CHECK 2
Check for causes of drop in low pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the error points.
Defective
low pressure
control
[In both cooling
and heating]
(See ∗1.)
Abnormally low
[In cooling]
low-pressure
(Low evaporating If the indoor unit
temperature)
electronic
expansion valve is
throttled too much:
(See ∗2.)
Defective electronic
expansion valve
control
[In heating]
If the outdoor unit
electronic
expansion valve
excessively
throttled:
(See ∗3.)
[In cooling]
Low suction air
temperature of
the evaporator
[In heating]
Less
circulation
quantity of
refrigerant
Degradation
in condensing
capacity
1: The "low pressure protection control" includes low pressure protection control and hot gas
Note:
2: In cooling, the indoor unit electronic expansion valve is used for "superheated degree control".
3: In heating, the outdoor unit electronic expansion valve (EV1) is used for "superheated
174
[In cooling]
Defective
compressor
capacity
control
Defective
low pressure
protection
control
Defective indoor
unit electronic
expansion valve
Defective
control
Defective outdoor
unit electronic
expansion valve
Defective
control
Low suction air
temperature of
indoor unit
Defective suction air thermistor of indoor unit
Low suction air temperature of outdoor unit
Defective outdoor air temperature thermistor of outdoor unit
High pipe
resistance
Inadequate refrigerant quantity
Moisture choke
Dirty
evaporator
Decreased
fan output
Decreased
fan airflow
High air
rate
passage
resistance
bypass control.
degree control of outdoor unit heat exchanger".
←Are the electrical characteristics normal?
Defective low pressure sensor
←Is the pressure value checked with the Service Checker
Defective service monitor PCB
corresponding to the measurement of the pressure sensor?
←Are the electrical characteristics normal?
Defective low pressure sensor
←Are the coil resistance and insulation normal?
Defective hot gas solenoid valve
←Is the pressure value checked with the Service Checker
Defective service monitor PCB
corresponding to the measurement of the pressure sensor?
←Are the coil resistance and insulation normal?
Defective valve coil
Defective valve body
←Check for the thermistor resistance and connection.
Defective gas pipe
thermistor of indoor unit
Defective liquid pipe
←Check for the thermistor resistance and connection.
thermistor of indoor unit
←Is the pressure value checked with the Service Checker
Defective service monitor PCB
corresponding to the measurement of the pressure sensor?
←Are the coil resistance and insulation
Defective valve coil
normal?
Defective valve body
←Are the electrical characteristics normal?
Defective low pressure sensor
←Check for the thermistor resistance and
Defective suction pipe thermistor
connection.
Defective service monitor PCB
←Is the suction air temperature not less than 57˚F
Short circuit
←Is the indoor air temperature not less than 57˚F
Low outdoor air temperature
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Is the outdoor air temperature not less than 5˚F?
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←Does the piping length fall in the permissible range?
Abnormal piping length
←Conduct visual checks for pipe conditions.
Bent or crashed pipe
←Is there any temperature difference caused before
Clogging of foreign particles
and after the filter or branch pipe?
Stop valve closed
←Check to be sure the stop valve is open.
←Refer to troubleshooting "U0".
←Eliminate moisture by vacuum operation.
←Is the heat exchanger clogged?
Defective fan motor
Defective service monitor PCB
(Including capacity setting)
Dirty filter
Obstacle
Troubleshooting by Remote Controller
←Can the fan motor be rotated with hands?
Are the motor coil resistance and insulation normal?
←If a spare PCB is mounted, is the capacity
setting properly made?
←Is the air filter clogged?
←Is there any obstacle in the air passage?
Service Diagnosis