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Heating operation does not work.•
Is there voltage of 208 / 230 VAC between pin1
and pin 2 at connector CN912?
Yes
No
Disconnect the lead wire leading to the compressor.
3 minutes after turning on the power supply, start EMERGENCY
OPERATION in HEAT mode.
1.
2.
Turn off power supply of indoor and outdoor unit, and discon-
nect the connector CN781 in the outdoor electronic control P.C.
board.
3 minutes after turning ON the power supply, start EMER-
GENCY OPERATION in HEAT mode.
1.
2
.
Turn OFF power supply of indoor and outdoor unit.
Is there voltage 12 VDC be-
tween the connector CN781
pin 5 (+) and pin 3 (-)?
No
Disconnect the connec-
tor CN912 in noise fi lter
P.C. board. Is there normal
resistance to R.V. coil?
No
Replace the R.V. coil.
Replace the 4-way valve.
Replace the noise fi lter P.C. board.
Yes
Replace the electronic
control P.C. board.
Cooling operation does not work.
•
Is there voltage of 208 / 230 VAC between pin1
and pin 2 at connector CN912?
Disconnect the lead wire leading to the compressor.
3 minutes after turning on the power supply, start EMERGENCY
OPERATION in COOL mode.
1.
2.
Turn OFF power supply of indoor and outdoor unit, and
disconnect the connector CN781 in the outdoor electronic
control P.C. board.
3 minutes after turning ON the power supply, start EMER-
GENCY OPERATION in COOL mode.
1.
2
.
Yes
Is there voltage 12 VDC between the connector
CN781 pin 5 (+) and pin 3 (-)?
No
Replace the noise fi lter P.C. board.
Replace the outdoor electronic control P.C. board.
No
Replace the 4-way valve.
If the connector CN912 is not
connected or R.V. coil is open,
voltage occurs between terminals
even when the control is OFF.
Yes
The cooling operation or heating operation does not operate.
MUZ-D30/36
C Check of R.V. coil