Daikin ERSQ 011AAV1 Service Manual page 219

ESIE09-08
[CHECK 2] Check for causes of drop in low pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the faulty points.
Abnormally low
low-pressure
[Heating]
(Low evaporating
(See *1.)
temperature)
Faulty electronic
expansion valve
control
[In heating]
If the outdoor unit
electronic
expansion valve
excessively
throttled:
(See *2.)
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 bypass control. For details, refer to P.61.
*2: In heating, the outdoor unit electronic expansion valve (EV1) is used for "superheated degree control of outdoor unit heat exchanger".
(For details, refer to P.51.)
Troubleshooting
Troubleshooting by Indication on the Remote Controller
Faulty outdoor Faulty valve coil
unit electronic
expansion valve
Faulty valve body
Faulty low pressure sensor
Faulty
Faulty suction pipe thermistor
control
Faulty control PCB
Low suction air temperature of outdoor unit
Faulty outdoor temperature thermistor of outdoor unit
Abnormal piping length
High pipe
Bent or crashed pipe
resistance
Clogging of foreign particles
Stop valve closed
Inadequate refrigerant quantity ←Refer to P.189.
Moisture choke
←Eliminate moisture by vacuum operation.
Dirty
←Is the heat exchanger clogged?
evaporator
Decreased
fan output
Decreased
fan airflow
High air
rate
passage
resistance
←Are the coil resistance and insulation normal?
←Are the electrical characteristics normal?
←Check for the thermistor resistance and
connection.
←Is the outdoor temperature not less than -15°C
←Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←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.
←Can the fan motor be rotated with hands?
Faulty fan motor
Are the motor coil resistance and insulation normal?
Faulty control PC board
←If a spare PC board is mounted, is the capacity
(Including capacity setting)
setting properly made?
Dirty filter ←Is the air filter clogged?
Obstacle
←Is there any obstacle in the air passage?
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