Mitsubishi Electric MUZ-HJ25VA-E2 Service Manual page 46

F Check of compressor start failure
Make sure that ~ is normal.
•Electrical circuit check
. Contact of the compressor connector (Including CN61)
. Output voltage of inverter P.C. board and balance of them (See 11-5. )
. Direct current voltage between DB61(+) and (-) on the inverter P.C. board
. Voltage between outdoor terminal block S1-S2
Does the compressor run for 10 seconds or
more after it starts?
No
After the compressor is heated with a drier,
does the compressor start?
Yes
Compressor start failure. Activate pre-heat control.
(Refer to 10-2. "PRE-HEAT CONTROL SETTING")
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 thermistor normal? (Refer to 11-6.1.)
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.)
Thermistor
Defrost
Discharge temperature
Fin temperature
Outdoor heat exchanger temperature
MUZ-HJ50/60/71VA only.
OBH648F
Yes
No
1
Yes
Yes
Symbol
RT61 Between CN641 pin 1 and pin 2
RT62 Between CN641 pin 3 and pin 4
RT64 Between CN642 pin 1 and pin 2
RT68 Between CN644 pin 1 and pin 3
Check the refrigerant circuit.
Check the stop valve.
Replace the compressor.
Replace the thermistor except RT64. When RT64
No
is abnormal, replace the inverter P.C. board.
Replace the inverter P.C. board.
No
Connector, Pin No.
46
1
Heat the compressor with
a drier for about 20 minutes.
Do not recover refrigerant
gas while heating.
Heating part
Board
Inverter P.C. board