Mitsubishi Electric Mr.Slim PKH Series Service Manual page 20

Abnormal point and detection method
Error Code
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: for 3 minutes, 3
minutes after the compressor started.
Abnormal if it stays under -15: for 3
minutes again within 16 minutes after
6-minute resume prevention mode.
2 Overheating protection (Heating mode)
The units is in 6 minute resume
P6
prevention mode if pipe <condenser /
evaporator> temperature is detected as
over 70: after the compressor started.
Abnormal if the temperature of over
70: is detected again within 30 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 °C ] (TH-TH1)
TH: Lower temperature between:
liquid pipe temperature (TH2) and
condenser/evaporator temperature
(TH5)
TH1: Intake 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
heating 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 [ (TH5-TH1)
OC330C
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)
(Heating mode)
1 Clogged filter (reduced airflow)
2 Short cycle of air path
3 Over-load (high 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)
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
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.
20
Countermeasure
(Cooling or drying mode)
1 Check clogs of the filter.
2 Remove shields.
4 Refer to 10-7-1.
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 10-7-1.
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.
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)'.
23Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
)