Mitsubishi Electric Mr. Slim PCA Series Service Manual page 22

Abnormal point and detection method
Check code
Freezing/overheating protection is work-
ing
1 Freezing protection (Cooling mode)
In case when
outside temperature > 4°F [ 20:]
The unit is in 6-minute resume preven-
tion mode if pipe <liquid or condenser/
evaporator> temperature stays under
5°F [ 15:] for 3 minutes, 3 minutes
after the compressor started.
Abnormal if it stays under 5°F [ 15:]
for 3 minutes again within 16 minutes
after 6-minute resume prevention mode.
In case when
outside temperature [ 4°F [ 20:]
The unit is in 6-minute resume preven-
tion mode if pipe <liquid or condenser/
P6
evaporator> temperature stays under
31°F [ 35:] for 3 minutes, 3 minutes
after the compressor started.
Abnormal if it stays under 31°F [ 35:]
for 3 minutes again within 16 minutes
after 6-minute resume prevention mode.
2 Overheating protection (Heating mode)
The unit is in 6-minute resume
prevention mode if pipe <liquid or con-
denser/evaporator> temperature is
detected as over 158°F [70:] after the
compressor started. Abnormal if the tem-
perature of over 158°F [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: 5.4°F [ 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: 5.4°F [3°C] [ (TH5 TH1)
OCH585
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 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.
22
Countermeasure
(Cooling or drying mode)
1 Check clogs of the filter.
2 Remove shields.
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 shields.
4 Refer to 9-6. HOW TO CHECK THE
PARTS .
5 Check outdoor fan motor.
6–8Check 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)'.
23Check converse connection of extension
pipe or converse wiring of indoor/outdoor
unit connecting wire.
)