Mitsubishi Electric Mr.SLIM PCA-M140KA Service Manual page 37

Abnormal point and detection method
Check code
Freezing/overheating protection is
operating
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 compressor started.
Abnormal if it stays under −15˚C for 3
minutes again within 16 minutes after
6-minute resume prevention mode.
Overheating protection (Heating mode)
The unit is in 6-minute resume
P6
prevention mode if pipe <liquid or
condenser/evaporator> temperature
is detected as over 70˚C after the
compressor started. Abnormal if the
temperature of over 70˚C 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: 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
OCH659
(Cooling or drying mode)
Clogged filter (reduced airflow)
Short cycle of air path
Low-load (low temperature)
operation out of the tolerance
range
Defective indoor fan motor
• Fan motor is defective.
• Indoor controller board is defec-
tive.
Defective outdoor fan control
Overcharge of refrigerant
Defective refrigerant circuit
(clogs)
(Heating mode)
Clogged filter (reduced airflow)
Short cycle of air path
Over-load (high temperature)
operation out of the tolerance
range
Defective indoor fan motor
• Fan motor is defective.
• Indoor controller board is defec-
tive.
Defective outdoor fan control
Overcharge of refrigerant
Defective refrigerant circuit
(clogs)
Bypass circuit of outdoor unit
is defective.
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
(TH−TH1) Converse connection of
extension pipe (on plural units
connection)
Converse wiring of indoor/
outdoor unit connecting wire
(on plural units connection)
Defective detection of indoor
room temperature and pipe
<condenser/evaporator>
temperature thermistor
Stop valve is not opened
completely.
(TH5−TH1)
Cause
(Cooling or drying mode)
Check clogs of the filter.
Remove blockage.
Refer to "9-6. HOW TO CHECK THE
PARTS".
Check outdoor fan motor.
Check operating condition of refrigerant
circuit.
(Heating mode)
Check clogs of the filter.
Remove blockage.
Refer to "9-6. HOW TO CHECK THE
PARTS".
Check outdoor fan motor.
– Check operating condition of refrigerant
circuit.
– Check pipe <liquid or condenser/evapo-
rator> temperature with room tempera-
ture display on remote controller and
outdoor controller circuit board.
Pipe <liquid or condenser/evaporator>
temperature display is indicated by set-
ting SW2 of outdoor controller circuit
board as follows.
(
Conduct temperature check with outdoor
controller circuit board after connecting
'A-Control Service Tool(PAC-SK52ST)'.
Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
30
Countermeasure
)