Mitsubishi Electric MXZ-2A20NA-1 Service Manual page 50

• When heating, room does not get warm.
• When cooling, room does not get cool.
E E 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
COOL: 150V(48Hz) HEAT: 170V(64Hz)
Is voltage output? W1, W2
Is output balanced?
Is the input voltage to the outdoor electronic
control P.C. board 370V or more?
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?
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
W1 • After the outdoor fan starts running, wait for 1 minute
• The output voltage values have the tolerance of i20%.
W2 • The output differs depending on the capacity or the
No
Yes
No
Yes
or more before measuring the voltage.
number of indoor units to be operated.
No
Replace the power board.
No
Replace the
compressor.
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