Mitsubishi Electric Mr.SLIM PLP-6EAER1 Service Manual page 21

Abnormal point and detection method
Check code
Drain pump lock protection operation
Error postponement, if drain pump stops
for 5 seconds continuously while drain
pump is operating.
Drain pump is abnormal if above condi-
P5
tion is repeated 4 times after error post-
ponement is detected.
Freeze/overheat protection is operating
Freeze protection (Cooling mode)
The unit is in 6-minute resume preven-
tion 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 pre-
vention mode.
Overheat protection (Heating mode)
P6
The unit is in 6-minute resume 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 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
dry mode.
Cooling range: −3°C ≥ (TH−TH1)
TH: Lower temperature between liquid pipe
temperature (TH2) and condenser/
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: 3°C ≤ (TH5−TH1)
OCH783B
Cause
Malfunction of drain pump
Clogged drain pump
Contact failure of connector
Defective indoor controller
board
(Cooling or dry 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
Overload (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
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.
21
Countermeasure
Check if drain pump works.
Check if drain pump works.
Check contact failure of connector CNP
Press the indoor emergency switch (SWE)
to check the voltage between CNP - .
• If 13 V DC, replace the drain pump.
• If not 13 V DC, replace the indoor controller
board.
(Cooling or dry 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/evapora-
tor> temperature with room temperature
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.
)