Mitsubishi Electric SUZ-SWM40VA Technical & Service Manual page 23

D Check of compressor winding
Disconnect the connector between the compressor and the intelligent power module, and measure the resistance between the
compressor terminals.
<Measurement point>
Measure the resistance between the lead wires at 3 points.
BK-WH
BK-RD
WH-RD
<Judgement>
Refer to "10-4. TROUBLE CRITERION OF MAIN PARTS".
0 [Ω] ················Abnormal [short]
Infinite [Ω] ·······Abnormal [open]
NOTE: Be sure to zero the ohmmeter before measurement.
E Check of compressor operation time
Connect the compressor and activate the inverter. Then measure the
time until the inverter stops due to overcurrent.
<Operation method>
Start heating or cooling test run.
<Measurement>
Measure the time from the start of compressor to the stop of
compressor due to overcurrent.
F 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 resistance of thermistor normal?
(Refer to 10-6.)
Yes
Does the unit operate for 10 minutes or more
without showing thermistor abnormality?
Yes
OK
(Cause is poor contact.)
Thermistor
Defrost
Discharge temperature
Fin temperature
Ambient temperature
Outdoor heat exchanger temperature RT68
OCH718A
Replace the thermistor except RT64.
When RT64 is abnormal, replace the inverter
No
P.C. board.
Replace the inverter P.C. board.
No
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
Between CN671 pin5 and pin6
23
<<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
Board
Inverter
P.C. board