Mitsubishi Electric PLA-RP35EA Service Manual page 21

Abnormal point and detection method
Check code
Drain pump lock protection operation
1 Error postponement, if drain pump stops
for 5 seconds continuously while drain
pump is operating.
2 Drain pump is abnormal if above condi-
tion is repeated 4 times after error post-
P5
ponement is detected.
Freeze/overheat protection is operating
1 Freeze protection (Cooling mode)
The unit is in 6-minute resume preven-
tion 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 pre-
vention mode.
2 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: 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 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 : -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 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)
OCH626A
Cause
1 Malfunction of drain pump
2 Clogged drain pump
3 Contact failure of connector
4 Defective indoor controller
board
(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 defec-
tive.
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 defec-
tive.
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.
21
Countermeasure
1 Check if drain pump works.
2 Check if drain pump works.
3 Check contact failure of connector CNP
4 Press the indoor emergency switch (SWE)
to check the voltage between CNP1-3.
•If 13 V DC, change the drain pump.
•If not 13 V DC, change the indoor con
troller board.
(Cooling or drying mode)
1 Check clogs of the filter.
2 Remove blockage.
4 Refer to "9-6. HOW TO CHECK THE
PARTS".
5 Check outdoor fan motor.
67 Check operating condition of refrigerant
circuit.
(Heating mode)
1 Check clogs of the filter.
2 Remove blockage.
4 Refer to "9-6. HOW TO CHECK THE
PARTS".
5 Check outdoor fan motor.
6–8 Check operating condition of refrigerant
circuit.
1–4 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)'.
23 Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
)