Mitsubishi MUY-A15NA, Service Manual

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G G
Check of outdoor thermistors
• When OPERATION INDICATOR lamp flashes 6-time.
• When thermistor is abnormal.
No
Yes
No
Yes
Reconnect the connector CN661 on the outdoor electronic control P.C. board and CN3 on the power board, and
disconnect the lead wire leading to the compressor.
3 minutes after turning on the power supply, start EMERGENCY OPERATION.
Defrost (MUZ)
Discharge temperature
Outdoor heat exchanger temperature
Ambient temperature
Fin temperature
Thermistor
Symbol
RT61
RT62
RT68
RT65
RT64
Connector, Pin No. Board
Between CN661 pin1 and pin2
Between CN661 pin3 and pin4
Between CN661 pin7 and pin8
Between CN663 pin1 and pin2
Between CN3 pin1 and pin2
The outdoor electronic control P.C. board
The outdoor power board
Disconnect the connector in the outdoor electronic control P.C. board or the outdoor power board
(see below table), and measure the resistance of thermistor. Is the thermistor normal?
(Refer to 10-6.3.)
Does the unit operate for 10 minutes or more without
showing thermistor abnormality?
Replace the thermistor.
Normal
Replace the outdoor electronic
control P.C. board.
Check of R.V. coil
H
Disconnect connector (CN61) between
the compressor and intelligent power
module.
Turn ON the power supply and press
EMERGENCY OPERATION switch
twice (HEAT mode).
Is there 208/230V AC between CN721
1
and
2
on the power P.C.board 3 minutes
after the power supply is turned ON?
Yes
No
Replace the
power P.C. board.
Replace the 4-way valve.
Replace the 4-way valve.
Disconnect connector (CN61) between
the compressor and the intelligent power
module.
Turn ON the power supply and press
EMERGENCY OPERATION switch once
(COOL mode).
Is there 208/230V AC between CN721
1
and
2
on the power P.C. board 3 minutes
after the power supply is turned ON?
No
Yes Replace the
power P.C. board.
w
First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 10-4.
w
In case CN721 is not connected or R.V. coil is open, voltage is generated between the
terminal pins of the connector although any signal is not being transmitted to R.V. coil.
Check if CN721 is connected.
CN721
Power P.C. board
(Soldered side)
Unit operates COOL mode even if it is set to HEAT mode.
Unit operates HEAT mode even if it is set to COOL mode.
MUZ-A24 MUY-A24
MUZ-A09/12/15/17
OB451--2.qxp 06.3.29 9:49 AM Page 45