How To Check Inverter/Compressor - Mitsubishi Electric MXZ-2B20NA Service Manual

• 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 the compressor
and the power board/outdoor power P.C. board. 3 minutes after the power supply is turned ON,
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
Is output balanced ?
Yes
Is the input voltage to the electronic control
P.C. board/outdoor control P.C. board
370 V or more (MXZ-2B/3B/4B)/350V or
more (MXZ-5B)?
Yes
Turn OFF the power supply of indoor and
outdoor unit, and measure the compressor
winding resistance between the compressor
terminals.
Is the 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
OBH560G
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
No
Replace the power board/
outdoor power P.C. board.
No
Replace the
compressor.
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