Mitsubishi Electric SLZ-KF25VA2 Technical & Service Manual page 19

Check code
Abnormal point and detection method
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 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 units is in 6-minute resume
prevention mode if pipe <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 10 minutes
after 6-minute resume prevention mode.
P6
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: 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
OCH616
(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
(clogging)
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
Converse connection of
extension pipe (on plural units
(TH−TH1)
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)
19
Cause
(Cooling or drying mode)
1 Check clogging 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 clogs 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.
(
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.
Countermeasure
)