Mitsubishi Electric PUHZ-FRP71VHA2 Service Manual page 34

Check Code
Abnormal points and detection method
Serial communication error
Abnormal if serial communication
between outdoor controller circuit
board and outdoor power circuit board is
defective.
Ed
(0403)
Abnormal if communication between
outdoor controller circuit board and
M-NET board is not available.
Pipe temperature
<Cooling mode>
Detected as abnormal when the pipe tem-
perature is not in the cooling range 3 min-
utes after compressor start and 6 minutes
after the liquid or condenser/evaporator pipe
is out of cooling range.
Note 1: It takes at least 9 minutes to detect.
Note 2: Abnormality P8 is not detected in
drying mode.
Cooling range: Indoor pipe temperature
(TH2 or TH5) – intake temperature
(TH1) [ −3_C
TH: Lower temperature between liquid pipe
temperature and condenser/
evaporator temperature
P8
<Heating mode>
When 10 seconds have passed after the
compressor starts operation and the hot
adjustment mode has finished, the unit is
detected as abnormal when condenser/
evaporator pipe temperature is not in heat-
ing range within 20 minutes.
Note 3: It takes at least 27 minutes to
detect abnormality.
Note 4: It excludes the period of defrosting
(Detection restarts when defrosting
mode is over)
Heating range: 3_C [ (Condenser/
Evaporator temperature (TH5) –
intake temperature (TH1))
Abnormal refrigerant circuit
During Cooling, Dry, or Auto Cooling
operation, when the following are
regarded as failures when detected for
one second.
a) The compressor continues to run for 30
or more seconds.
b) The liquid pipe temperature or the
PL
condenser/evaporator temperature is
75°C or more.
These detected errors will not be
cancelled until the power source is reset.
OCH665B
Cause
1 Breaking of wire or contact
failure of connector CN2
between the outdoor controller
circuit board and the outdoor
power circuit board
2 Breaking of wire or contact
failure of connector CN4
between the outdoor controller
circuit board and the outdoor
power circuit board
3 Defective communication circuit
of outdoor power circuit board
4 Defective communication circuit
of outdoor controller circuit board
for outdoor power circuit board
1 Breaking of wire or contact
failure of connector between
outdoor controller circuit board
and M-NET board
2 Contact failure of M-NET board
power supply line
3 Noise has entered into M-NET
transmission wire.
1 Slight temperature difference
between indoor room
temperature and pipe <liquid
or condenser / evaporator>
temperature thermistor
• Shortage of refrigerant
• Disconnected holder of pipe
<liquid or condenser /
evaporator> thermistor
• Defective refrigerant circuit
2 Reverse connection of
extension pipe (on plural units
connection)
3 Reverse wiring of indoor/
outdoor unit connecting wire
(on plural units connection)
4 Defective detection of indoor
room temperature and pipe
<condenser / evaporator>
temperature thermistor
5 Stop valve is not opened
completely.
1 Abnormal operation of 4-way
valve
2 Disconnection of or leakage in
refrigerant pipes
3 Air into refrigerant piping
4 Abnormal operation (no rotation)
of indoor fan
· Defective fan motor.
· Defective indoor control
board.
5 Defective refrigerant circuit
(clogging)
34
Judgment and action
12 Check connection of each connector CN2
and CN4 between the outdoor controller
circuit board and the outdoor power circuit
board.
3 Replace outdoor power circuit board.
4 Replace outdoor controller circuit board.
1 Check disconnection, looseness, or breaking
of connection wire between outdoor controller
circuit board (CNMNT) and M-NET board (CN5).
2 Check disconnection, looseness, or breaking of
connection wire between outdoor controller cir-
cuit board (CNVMNT) and M-NET board (CND).
3 Check M-NET transmission wiring method.
1–4 Check pipe <liquid or condenser /
evaporator> temperature with room
temperature display on remote
controller and outdoor controller circuit
board.
Pipe <liquid or condenser / evaporator>
temperature display is indicated by
setting SW2 of outdoor controller circuit
board as follows.
Conduct temperature check with outdoor
(
controller circuit board after connecting
'A-Control Service Tool (PAC-SK52ST)'.
Temperature display of indoor condenser/
Temperature display of indoor liquid pipe
evaporator pipe Indoor 1
Indoor 1
1 2 3 4 5 6 1 2
ON
OFF
Temperature display of indoor condenser/
Temperature display of indoor liquid pipe
evaporator pipe Indoor 2
Indoor 2
1 2 3 4 5 6 1 2
ON
OFF
A-Control Service Tool SW2 setting
23Check reverse connection of extension
pipe or reverse wiring of indoor/outdoor
unit connecting wire.
1 When this error occurs, be sure to
replace the 4-way valve.
2 Check refrigerant pipes for disconnection or
leakage.
3 After the recovery of refrigerant, vacuum
dry the whole refrigerant circuit.
4 Refer to section "10-6. HOW TO CHECK
THE PARTS".
5 Check refrigerant circuit for operation.
To avoid entry of moisture or air into
refrigerant circuit which could cause
abnormal high pressure, purge air in
refrigerant circuit or replace refrigerant.
)
3
4 5 6
ON
OFF
3 4 5 6
ON
OFF