Mitsubishi Electric MUZ-HA VF Series Service Manual page 31

10-4. TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the
power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp blinks.
HR25/35/42/50VF
OPERATION INDICATOR
Abnormal
No.
point
Left/Upper lamp blinks. *1
0.5-second ON
Miswiring
1 or serial
signal
0.5-second OFF
Left/Upper lamp blinks. *1
Indoor coil
2-time blink
thermistor
2
Room
2.5-second OFF
temperature
thermistor
Left/Upper lamp blinks. *1
3-time blink
3 Indoor fan
motor
Left/Upper lamp blinks. *1
4-time blink
Indoor
4 control
system
Left/Upper lamp blinks. *1
5-time blink
Outdoor
5 power
system
Left/Upper lamp blinks. *1
6-time blink
6 Outdoor
thermistors
Left/Upper lamp blinks. *1
7-time blink
Outdoor
7 control
system
Left/Upper lamp blinks. *1
14-time blink or more
2.5-second OFF
Other
8 abnormality
*2
Outdoor Left/Upper lamp lights up.
9 control
system
*1 Left lamp: HR25/35/42/50VF
Upper lamp: HR60/71VF
*2 Refer to *2 on 10-3. INSTRUCTION OF TROUBLESHOOTING.
OBH822H
HR60/71VF
OPERATION INDICATOR
Operation indicator lamp
2.5-second OFF
2.5-second OFF
2.5-second OFF
2.5-second OFF
2.5-second OFF
Lit
Blinking
Not lit
Symptom Condition
The serial signal from the outdoor
unit is not received for 6 minutes.
The indoor coil or the room
temperature thermistor is short or
open circuit.
The rotational frequency feedback
signal is not emitted during the
indoor fan operation.
It cannot properly read data in the
nonvolatile memory of the indoor
electronic control P.C. board.
It consecutively occurs 3 times
that the compressor stops for
Indoor unit and
overcurrent protection or startup
outdoor unit do
failure protection within 1 minute
not operate.
after startup.
The outdoor thermistors short or
open circuit during the compressor
operation.
It cannot properly read data in the
nonvolatile memory of the inverter
P.C. board or the outdoor elec-
tronic control P.C. board.
An abnormality other than the
above is detected.
An abnormality of the indoor
thermistors, the defrost thermistor
or ambient temperature thermistor
is detected.
Outdoor unit It cannot properly read data in the
does not nonvolatile memory of the inverter
operate P.C. board.
31
Remedy
• Refer to 10-6. "How to
check miswiring and serial
signal error".
• Refer to the characteristics
of indoor coil thermistor, and
the room temperature
thermistor (10-7.).
• Refer to 10-6. "Check of
indoor fan motor".
• Replace the indoor
electronic control P.C. board.
• Refer to "How to check of
inverter/compressor".
Refer to outdoor unit service
manual.
• Check the stop valve.
• Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
• Replace the inverter P.C.
board or the outdoor
electronic control P.C. board.
Refer to outdoor unit service
manual.
• Check the stop valve.
• Check the 4-way valve.
• Check the abnormality in
detail using the failure mode
recall function for outdoor
unit.
• Refer to TEST POINT
DIAGRAM AND VOLTAGE"
on the service manual of
indoor and outdoor unit for
the characteristics of the
thermistors. (Do not start the
operation again without
repair to prevent hazards.)
• Check the blinking pattern of
the LED on the inverter P.C.
board.