Mitsubishi Electric PEY Series Service Manual page 32

TROUBLESHOOTING
Error Code Abnormal point and detection method
Freezing/overheating protection is
operating
1 Freezing protection (Cooling mode)
The unit is in 6-minute resume prevention
mode if pipe <liquid or condenser/
evaporator> temperature stays under
-15°C for 3 minutes, 3 minutes after the
P6
compressor started. Abnormal if it stays
under -15°C for 3 minutes again within 16
minutes after 6-minute resume prevention
mode.
Pipe temperature
<Cooling mode>
Detected as abnormal when the pipe
temperature is not in the cooling range 3
minutes 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 : -3 deg ≥ (TH-TH1)
P8
TH: Lower temperature between: liquid pipe
temperature (TH2) and condenser/
evaporator temperature (TH5)
TH1: Intake temperature
Pipe temperature thermistor/ Condenser-
Evaporator (TH5)
1 The unit is in 3-minute resume protection
mode if short/open of thermistor is
detected. Abnormal if the unit does not get
back to normal within 3 minutes. (The unit
returns to normal operation, if it has
normally reset.)
2 Constantly detected during cooling, drying,
and heating operation (except defrosting)
Short: 90°C or more
Open: -40°C or less
P9
HWE1305A
Cause
(Cooling or drying mode)
1 Clogged filter (reduced airflow)
2 Short cycle of air path
3 Low load (low temperature)
operation out of the tolerance
range
4 Defective indoor fan motor
• Fan motor is defective.
• Indoor controller board is
defective.
5 Defective outdoor fan control
6 Overcharge of refrigerant
7 Defective refrigerant circuit
(clogs)
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 Converse connection of
extension pipe (on plural units
connection)
3 Converse 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 Defective thermistor
characteristics
2 Contact failure of connector
(CN44) on the indoor controller
board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Temperature of thermistor is
90°C or more or -40°C or less
caused by defective refrigerant
circuit.
5 Defective indoor controller
board
32
Countermeasure
(Cooling or drying mode)
1 Check clogs of the filter.
2 Remove blockage.
4 Refer to 9-6.
5 Check outdoor fan motor.
6 7 Check operating condition of refrigerant
circuit.
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)'.)
2 3 Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
1–3 Check resistance value of thermistor.
For characteristics, refer to (P1) above.
2 Check contact failure of connector (CN44)
on the indoor controller board.
Refer to 9-7.
Turn the power on and check restart after
inserting connector again.
4 Operate in test run mode and check pipe
<condenser/evaporator> temperature with
outdoor controller circuit board. If pipe
<condenser/evaporator> temperature is
extremely low (in cooling mode) or high (in
heating mode), refrigerant circuit may have
defect.
5 Operate in test run mode and check pipe
<condenser/evaporator> temperature with
outdoor control circuit board. If there is
extreme difference with actual pipe
<condenser/evaporator> temperature,
replace indoor controller board.
There is no abnormality if none of above
comes within the unit.
Turn the power off and on again to operate.
( In case of checking pipe temperature with
outdoor controller circuit board, be sure to
connect A-control service tool (PAC-SK52ST).)