Mitsubishi Electric MSZ-AP20VG-E3 Service Manual page 24

10-3. INSTRUCTION OF TROUBLESHOOTING
1. Check of the unit.
*2 There is possibility that diesel explosion may occur due to the air mixed in the refrigerant circuit.
Start
Indoor unit operates.
Outdoor unit does
not operate.
Outdoor unit Outdoor unit
operates only does not
in Test Run operate even
operation. *1 in Test Run
operation. *1
Check room
Refer to "How
temperature to check
thermistor.
inverter/com-
Refer to 10-
pressor".
7. "Test point
diagram and
voltage".
Left lamp Left lamp
Blink on and 2-time blink
off at 0.5-sec-
Cause:
ond intervals Indoor unit
Cause: • Trouble
Indoor/Outdoor of room
unit temperature
• Miswiring or / indoor coil
trouble of se- thermistor
rial signal
Refer to 10- Check room
6. "How to temperature
check mis- thermistor
wiring and and indoor
serial signal coil thermis-
error". tor. Refer to
10-7."Test
point diagram
and voltage".
OBH838C
First, ensure that there are no leakage points on the valves, flare connections, etc. that allow the
air to flow into the refrigerant circuit, or no blockage points (e.g. clogged or closed valves) in the
refrigerant circuit that cause an increase in pressure.
If there is no abnormal point like above and the system operates cooling and heating modes nor-
mally, the indoor thermistor might have a problem, resulting in false detection.
Check both the indoor coil thermistor and the room temperature thermistor, and replace faulty
thermistor(s), if any.
NOTE: Do not start the operation again without repair to prevent hazards.
Indoor unit operates.
Outdoor unit does
not operate normally.
Indoor unit
Unit does not
operates, when
operate nor-
the emergency
mal operation
operation switch
in COOL or
is pressed.
HEAT mode.
Refer to Refer to 10-6.
"Check of R.V. "Check of remote
coil". controller and
indoor elec-
tronic control P.C.
board".
Left lamp
Left lamp
3-time blink 4-time blink
Cause: Cause:
Indoor unit Indoor unit
• Trouble of • Trouble
indoor fan of indoor
motor unit control
system
Refer to 10- Replace the
6. "Check indoor elec-
of indoor fan tronic control
motor". P.C. board.
Indoor unit does
OPERATION INDICATOR
not receive the
lamp on the indoor unit is
signal from re-
blinking ON and OFF.
mote controller.
Indoor unit does
not operate, when
the emergency
operation switch
is pressed.
1. Check indoor/out-
door connecting wire.
(Check if the power is
supplied to the indoor
unit.)
2. Refer to 10-6. "Check
of indoor P.C. board
and indoor fan motor".
Left lamp Left lamp
5-time blink 6-time blink
Cause:
Cause:
Outdoor unit Outdoor unit
• Outdoor • Trouble of
thermistor in
power sys-
tem abnor- outdoor unit
mality
Refer to Refer to
"How to "Check of
check outdoor ther-
inverter/com- mistors".
pressor".
24
*1 "Test Run operation" means
the operation within 30 minutes
after the emergency operation
switch is pressed.
If blinking of OPERATION INDI-
CATOR lamp cannot be checked,
it can be checked with failure
mode recall function.
Refer to outdoor unit service manual.
Left lamp Left lamp
7-time blink 14-time blink
Cause: or more
Outdoor unit Cause:
• Trouble of Outdoor unit
outdoor con- • Other ab-
trol system normality
Indoor/Out-
door unit
• Trouble of
thermistors
*2
Replace the • Check "Flow
inverter P.C. chart of the
board or detailed
the outdoor outdoor unit
electronic failure mode
control P.C. recall func-
board. tion."
• Check
thermistors.
Refer to
"Test point
diagram and
voltage" in
the service
manual of
indoor and
outdoor unit.