Mitsubishi Electric SLZ Series Technical & Service Manual page 16

Check code
Abnormal point and detection method
Drain pump lock protection operation
1 Suspected abnormality, if drain pump
stops for 5 seconds continuously with
drain pump on.
Drain pump will be restarted after turning
P5
off for 10 seconds.
2 Drain pump is abnormal if the condition
above is detected 4 times during
operation.
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
-5°F [-15°C] for 3 minutes after the
compressor started. Abnormal if it stays
under -5°F [-15°C] for 3 minutes again
within 16 minutes after 6-minute resume
prevention mode.
Overheating protection (Heating mode)
The units is in 6-minute resume prevention
mode if pipe <condenser/evaporator>
temperature is detected as over 158°F
P6
[70°C] after the compressor started.
Abnormal if the temperature of over 158°F
[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
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)
TCH118
Cause
1 Malfunction of drain pump
2 Clogged drain pump
Disconnected drain pump
Defective indoor controller board
(Cooling or drying mode)
1 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
defective.
Defective outdoor fan control
Overcharge of refrigerant
Defective refrigerant circuit
(clogging)
(Heating mode)
1 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
defective.
Defective outdoor fan control
Overcharge of refrigerant
Defective refrigerant circuit
(restriction)
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
Reverse connection of extension
pipe (on plural units connection)
Reverse 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.
16
*1: only P-series outdoor unit
Countermeasure
12 Check if drain pump works.
Check if connector (CNP) is connected.
Turn the emergency operation switch (SWE)
on and check the voltage between CNP 1– .
• Replace drain pump if the output is 13V DC.
• Replace indoor controller board if the output
is under 13V DC.
(Cooling or drying mode)
1 Check cleanliness of the filter.
Remove blockage.
Refer to "8-7-2. DC Fan Motor (Fan Motor /
Indoor Controller Board)".
Check outdoor fan motor.
Check operating condition of refrigerant
circuit.
(Heating mode)
1 Check cleanliness of the filter.
Remove blockage.
4 Refer to "8-7-2. DC Fan Motor (Fan Motor /
Indoor Controller Board)".
Check outdoor fan motor.
– Check operating condition of refrigerant
circuit.
Check pipe <liquid or condenser/
1–
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.
*1
(
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.
)