Mitsubishi Electric MXZ-2C30VA Service Manual page 104

• When heating, room does not get warm.
• When cooling, room does not get cool.
How to check inverter/compressor
Disconnect the terminal of the compressor or the connector (CNMC) between compressor and
the inverter P.C. board/the outdoor power P.C. board. 3 minutes after turning ON the
power supply, start EMERGENCY OPERATION.
Measure the voltage between each lead
wire leading to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Output voltage 50V-250V
Is proper output voltage detected?
Yes
(MXZ-2C)
Is output balanced?
Yes
Yes
Is the input voltage to the electronic control
P.C. board/the control P.C. board/the outdoor
control P.C. board 370V or more (MXZ-3C/4C/
5C)/350V or more (MXZ-6C) ?
Yes
Turn OFF the power supply, and measure the
compressor winding resistance between the
compressor terminals.
Is there resistance between each terminal normal?
(Refer to 11-5.)
Yes
Reconnect the lead wire of compressor, and turn ON
the power supply to indoor and outdoor unit.
3 minutes later, start EMERGENCY OPERATION.
Clarify the causes by counting time until the inverter stops.
0 to 10 seconds: compressor layer short
10 to 60 seconds: compressor lock
60 seconds to 5minutes: refrigerant circuit defective
5 minutes or more: normal
OBH584G
1 After the outdoor fan starts running, wait for 1 minute
or more before measuring the voltage.
The output voltage values have the tolerance of ± 20%.
2 The output differs depending on the capacity or the
number of indoor units to be operated.
No
1 2
No
(MXZ-3C/4C/5C/6C)
Replace the power board (MXZ-3C/4C/
No
5C/6C120)/outdoor power P.C. board
(MXZ-6C122).
No
Replace the
compressor.
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