Mitsubishi Electric PUHZ-W50VHA Technical Manual page 41

Abnormal point and detection method
Error Code
Freezing/overheating protection is
working
1 Freezing protection (Cooling mode)
The unit is in 6-minute resume
prevention mode if pipe <liquid or
2-phase> 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
prevention mode.
P6
2 Overheating protection (Heating mode)
The units is in 6 minute resume
prevention mode if pipe <2-phase>
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
temperature is not in the cooling range
3 minutes after compressor start and 6
minutes after the liquid or 2-phase 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 2-phase
temperature (TH5)
TH1: Target temperature
<Heating mode>
When 10 seconds have passed after the
P8
compressor starts operation and the hot
adjustment mode has fi nished, the unit is
detected as abnormal when 2-phase pipe
temperature is not in heating 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)
Cause
(Cooling or drying mode)
1 Clogged fi lter (reduced airfl ow)
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
defective.
5 Defective outdoor fan control
6 Overcharge of refrigerant
7 Defective refrigerant circuit
(clogs)
(Heating mode)
1 Clogged fi lter (reduced airfl ow)
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
defective.
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 TH1
temperature and pipe <liquid
or 2-phase>
temperature thermistor
• Shortage of refrigerant
• Disconnected holder of pipe
<liquid or 2-phase> thermistor
• Defective refrigerant circuit
2 Converse connection of
extension pipe (on plural units
connection)
3 Converse wiring of interface/
outdoor unit connecting wire (on
plural units connection)
4 Defective detection of
target temperature and pipe
<2-phase>
temperature thermistor
5 Stop valve is not opened
completely.
41
Countermeasure
(Cooling or drying mode)
1 Check clogs of the fi lter.
2 Remove shields.
4 Check indoor fan motor.
5 Check outdoor fan motor.
67 Check operating condition of refrigerant
circuit.
(Heating mode)
1 Check clogs of the fi lter.
2 Remove shields.
4 Check indoor fan motor.
5 Check outdoor fan motor.
6~8Check operating condition of refrigerant
circuit.
1~4 Check pipe <liquid or 2-phase>
temperature with target temperature
display on remote controller and outdoor
controller circuit board.
Pipe <liquid or 2-phase> 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)'.
23Check converse connection of extension
pipe or converse wiring of interface/outdoor
unit connecting wire.
)