Mitsubishi Electric Mr.Slim MUZ-A09NA Service Manual page 49

F Check of compressor operation time
MUZ-A09/12/15/17 MUY-A15/17
● Connect the compressor and activate the inverter. Then measure
the time until the inverter stops due to over current.
<<Operation method>>
Start heating or cooling operation by pressing EMERGENCY
OPERATION switch on the indoor unit.
(TEST RUN OPERATION: Refer to 7-7.)
<<Measurement>>
Measure the time from the start of outdoor fan running to the stop
of compressor due to overcurrent.
G Check of outdoor thermistors
Disconnect the connector of thermistor in the outdoor P.C. board (see
below table), and measure the resistance of thermistor.
Is the thermistor normal? (Refer to 10-6.1.
or 10-6.3.)
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-A09/12/15/17 MUY-A15/17
Thermistor
Defrost
Discharge temperature
Fin temperature
Ambient temperature
MUZ-A24 MUY-A24 MUZ-GA24 MUY-GA24
Thermistor
Defrost
Discharge temperature
Outdoor heat exchanger temperature
Ambient temperature
Fin temperature
No
Yes
No
Yes
Symbol Connector, Pin No.
RT61 Between CN641 pin 1 and pin 2
RT62 Between CN641 pin 3 and pin 4
RT64 Between CN642 pin 1 and pin 2
RT65 Between CN643 pin 1 and pin 2
Symbol Connector, Pin No.
RT61 Between CN661 pin 1 and pin 2
RT62 Between CN661 pin 3 and pin 4
RT68 Between CN661 pin 7 and pin 8
RT65 Between CN663 pin 1 and pin 2
RT64 Between CN3 pin 1 and pin 2
49
<<Judgement>>
0 second Compressor starts
1 second
Abnormal
(IPM failure)
(Compressor winding short)
2 seconds
Abnormal
(Compressor lock out)
(Starting defect)
Abnormal
(Poor contact,)
(Outdoor P.C. board defect)
10 seconds
(Disconnected connector)
Abnormal
(Refrigerant circuit defect)
(Closed valve)
10 minutes
Normal
Replace the thermistor except RT64.
When RT64 is abnormal, replace the inverter P.C.
board or the outdoor power board.
Replace the inverter P.C. board
or the outdoor power board.
Inverter P.C. board
Outdoor electronic control P.C. board
Outdoor power board
Board
Board