Mitsubishi Electric MUZ-FD25VA-E1 Service Manual page 30

Check of compressor winding
D
Disconnect the connector (CN61) between the compressor and
intelligent power module, and measure the resistance between the
compressor terminals.
<<Measurement point>>
at 3 points
BLK-WHT
BLK-RED
WHT-RED
<<Judgement>>
Refer to 11-4.
0["] ···············Abnormal [short]
Infinite["] ·······Abnormal [open]
NOTE: 1. Be sure to zero the ohmmeter before measurement.
Check of compressor operation time
E
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 8-3.)
<<Measurement>>
Measure the time from the start of compressor to the stop of compressor
due to over current.
Check of compressor start failure
F
Confirm that 1~4 is normal.
•Electrical circuit check
1Contact of the compressor connector (including CN61)
2Output voltage of inverter P.C.board and balance of them (See 11-5.B)
3Direct current voltage between DB61(+) and (-) on inverter P.C.board
4Voltage between outdoor terminal block S1-S2
Does the compressor run for 10 seconds
or more after it starts?
After the compressor is heated with a drier,
does the compressor start? w1
Compressor start failure. Activate pre-heat control.
(Refer to 10-2. "PRE-HEAT CONTROL SETTING")
w Measure the resistance between the
lead wires at 3 points.
Yes
No
No
Yes
<<Judgement>>
For reference
0 second
1 second
2 seconds
10 seconds
10 minutes
Check the refrigerant circuit.
Check the stop valve.
Replace the compressor
30
Compressor starts
Abnormal
(IPM failure)
(Compressor winding short)
Abnormal
(Compressor lock out)
(Starting defect)
Abnormal
(Poor contact,)
(Outdoor P.C.board defect)
(disconnected connector)
Abnormal
(Refrigerant circuit defect)
(closed valve)
Normal
w1
Heat the compressor with
a drier for about 20 minutes.
Do not recover refrigerant
gas while heating.
Heating part