Daikin VRV III-S RXYMQ36 48PVJU, Service Manual

Page: 219 / 264

SiUS34-907
210 Troubleshooting
Check for Causes of Rise in High Pressure
Referring to the Fault Tree Analysis (FTA) shown below, probe the faulty points.
*1: In cooling, it is normal if the outdoor unit electronic expansion valve (EV1) is fully open.
*2: In heating, the indoor unit electronic expansion valve is used for “subcooled degree control”.
(For details, refer to “Electronic Expansion Valve Control”.)
CHECK 1
Short circuit
Rise in high
pressure
Local
pressure
rise
High pipe
resistance
Stop valve closed
Bent or crashed pipe
Clogging of foreign
particles
←
Check to be sure the stop valve is open.
←
Conduct visual checks for pipe conditions.
←
Is there any temperature difference caused before
and after the filter or branch pipe.
[In cooling]
If the outdoor unit electronic
expansion valve is throttled:
(See *1.)
Faulty outdoor
unit electronic
expansion valve
Faulty indoor
unit electronic
expansion valve
Faulty valve coil
Faulty valve body
←
Are the coil resistance and insulation normal?
A temperature difference in excess of 50
°
F
between the inlet and the outlet is deemed to be abnormal.
Faulty
control
Faulty high pressure sensor
Faulty control PCB
←
Are the electrical characteristics normal?
←
Is the pressure value checked with the Service Checker
corresponding to the measurement of the pressure sensor?
←
Are the coil resistance and insulation
normal?
Faulty high
pressure
control
Faulty valve coil
Faulty valve body
[In heating]
If the indoor unit electronic
expansion valve excessively
throttled:
(See *2.)
Faulty
control
Faulty high pressure sensor
Faulty indoor unit
liquid pipe thermistor
Faulty control PCB
←
Are the electrical characteristics normal?
←
In the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the pressure value checked with the Service
Checker corresponding to the measurement of the
pressure sensor?
[In cooling]
High suction
air
temperature
of the
condenser
[In heating]
High suction air
temperature
of outdoor unit
Short circuit
High ambient temperature
←
Is the suction air temperature not more than
109.4
°
F?
←
Is the outdoor temperature not more than 109.4
°
F?
High suction
air temperature
of indoor unit
High ambient temperature
←
Is the suction air temperature not more than 80.6
°
F?
←
Is the indoor temperature not more than 80.6
°
F?
Faulty suction air thermistor of indoor unit
High suction air temperature of outdoor unit
Faulty outdoor temperature thermistor of outdoor unit
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
←
Is the outdoor temperature not more than 60.8
°
FWB?
←
Is the connector properly connected?
Are the thermistor resistance characteristics normal?
Degradation
in condensing
capacity
Dirty condenser
Mixing of non-condensable gas
←
Is the heat exchanger clogged? (In cooling)
←
Is air or else mixed in the refrigerant system?
Decreased
fan airflow
rate
Decreased
fan
output
Faulty fan
motor ←
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?
Faulty control
PCB
(Including
capacity setting)
High air
passage
resistance
Dirty filter
←
Is the air filter clogged?
Obstacle
←
Is there any obstacle in the air passage?
Excessive refrigerant charging
Improper model selection [In heating]
←
Refer to troubleshooting "
F6
".
←
Is the indoor unit too small compared to
the large-sized outdoor unit?