Mitsubishi Electric MXZ-2B30VA Service Manual page 79

• 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. 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
Is output balanced?
(MXZ-2B)
Is the input voltage to the outdoor electronic
control P.C. board 370V or more?
Turn OFF the power supply of indoor and outdoor
unit, and measure the compressor winding
resistance between the compressor terminals.
Is there resistance between each terminal normal?
(Refer to 11-5.)
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
OBH554D
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
Yes
No
Yes
(MXZ-3B/4B/5B)
Yes
Yes
Replace the inverter P.C. board or
No
power board.
No
Replace the
compressor.
79