Mitsubishi Electric M Series Service Manual page 32

Abnormal point and detection method
Error Code
Freezing/overheating protection is
working
1 Freezing protection (Cooling mode)
The unit is in six-minute resume preven-
tion mode if pipe <liquid or condenser/
evaporator> temperature stays under
-15:
compressor started. Abnormal if it stays
under -15:
within 16 minutes after six-minute
resume prevention mode.
2 Overheating protection (Heating mode)
The units is in six-minute resume
prevention mode if pipe <Liquid or con-
denser / evaporator> temperature is
detected as over 70:
compressor started. Abnormal if the
temperature of over 70:
detected again within 10 minutes after
six-minute resume prevention mode.
P6
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 :
TH: Lower temperature between: liquid
pipe temperature (TH2) and condens-
er/evaporator temperature (TH5)
P8 TH1: Intake temperature
<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 :
Cause
(Cooling or drying mode)
1 Clogged filter (reduced airflow)
2 Short cycle of air path
3 Low-load (low temperature)
operation beyond 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)
(Heating mode)
1 Clogged filter (reduced airflow)
2 Short cycle of air path
3 Over-load (high temperature)
operation beyond 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)
8 Bypass circuit of outdoor unit is
defective.
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
(TH-TH1) 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.
(TH5-TH1)
30
Countermeasure
(Cooling or drying mode)
1 Check clogging of the filter.
2 Remove shields.
4 Refer to 12-8. DC Fan motor (FAN MOTOR/
INDOOR CONTROLLER BOARD)
5 Check outdoor fan motor.
67 Check operating condition of refrigerant
circuit.
(Heating mode)
1 Check clogs of the filter.
2 Remove shields.
4 Refer to 12-8. DC Fan motor (FAN MOTOR/
INDOOR CONTROLLER BOARD)
5 Check outdoor fan motor.
6~8Check 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.
( Conduct temperature check with outdoor
controller circuit board after connecting
'A-Control Service Tool(PAC-SK52ST)'.
23 Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
© 2016 Mitsubishi Electric US, Inc.
)