Check Of Outdoor Thermistors; Check Of R.v. Coil - Mitsubishi Electric MUZ-GE09NA Service Manual

G Check of outdoor thermistors
Disconnect the connector of thermistor in the inverter P.C. board (see
below table), and measure the resistance of thermistor.
Is the resistance of thermistor normal? (Refer to 10-6.1.)
Reconnect the connector of thermistor.
Turn ON the power supply and press EMERGENCY OPERATION switch.
Does the unit operate for 10 minutes or more
without showing thermistor abnormality?
OK. (Cause is poor contact.)
MUZ-GE09/12/15NA/NA2/NAH/NAH2, MUZ-GE18NA/NAH, MUY-GE09/12/15NA/NA2, MUY-GE18NA
Thermistor
Defrost (MUZ)
Discharge temperature
Fin temperature
Ambient temperature
Outdoor heat exchanger temperature
MUZ-GE24NA, MUY-GE24NA
Thermistor
Defrost (MUZ)
Discharge temperature
Fin temperature
Ambient temperature
Outdoor heat exchanger temperature
H Check of R.V. coil
MUZ-GE09/12/15NA/NA2/NAH/NAH2, MUZ-GE18NA/NAH, MUZ-GE24NA
First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 10-4.
In case CN721 (MUZ-GE09/12/15/18)/CN602 (MUZ-GE24) is disconnected or R.V. coil is open, voltage is generated
between the terminal pins of the connector although no signal is being transmitted to R.V. coil. Check if CN721 (MUZ-
GE09/12/15/18)/CN602 (MUZ-GE24) is connected.
Unit operates COOL mode even if it is set to HEAT mode.
Disconnect connector between the
compressor and intelligent power module/
power module 1.
Turn ON the power supply and press
EMERGENCY OPERATION switch twice
(HEAT mode).
OBH549F
Yes
No
Yes
Symbol Connector, Pin No.
RT61 Between CN641 pin1 and pin2
RT62 Between CN641 pin3 and pin4
RT64 Between CN642 pin1 and pin2
RT65 Between CN643 pin1 and pin2
RT68 Between CN644 pin1 and pin3
Symbol Connector, Pin No.
RT61 Between CN671 pin1 and pin2
RT62 Between CN671 pin3 and pin4
RT64 Between CN673 pin1 and pin2
RT65 Between CN672 pin1 and pin2
RT68 Between CN671 pin5 and pin6
Is there 208/230 VAC between CN721 (MUZ-
GE09/12/15/18)/CN602 (MUZ-GE24)
on the inverter P.C. board 3 minutes after the
power supply is turned ON?
Replace the 4-way valve.
1
Intelligent power module: MUZ-GE09/12/15/18/24NA, MUY-GE09/12/15/18/24NA
Power module: Other models
54
Replace the thermistor except RT64. When RT64 is
No
abnormal, replace the inverter P.C. board.
Replace the inverter P.C. board.
Inverter P.C. board
Inverter P.C. board
and
Yes
Board
Board
Replace the inverter
No P.C. board.