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4) Treatment of Inverter and Compressor Troubles
If the compressor does not work when error codes 4240, 4250, 4340 or 4350 are detected, determine the point of
malfunction by following the steps in the LED monitor display and countermeasures depending on the check
code displayed, then perform the procedures below.
No. Check Item Symptoms Treatment
*1 [Cautions when measuring the voltage and current of the inverter’s power circuit.]
Since the voltage and current on the inverter’s power supply side and its output side do not have a sine waveform, the
measurement values will differ depending on the measuring instrument and the circuit measured.
In particular, as the inverter’s output voltage has a pulse waveform, the output frequency also changes, so differences in
measurement values will be great depending on the measuring instrument.
1 When checking if the inverter’s output voltage is unbalanced or not (relative comparison of the voltages between
each of the lines), if you are testing with a portable tester, be sure to use an analog tester.
Use a tester of a type which can be used to judge if the IPM or diode module is faulty.
In particular, in cases where the inverter’s output frequency is low, there are cases where the variations in measured
voltage values between the different wires will be great when a portable digital tester is used, when in actuality they
are virtually equal, and there is danger of judging that the inverter is faulty.
2 It is recommended when checking the inverter’s output voltage values (when measuring absolute values), that, if a
measuring device for business frequencies is used, a rectified voltage meter (with a
symbol) be used.
Correct measurement values cannot be obtained with an ordinary portable tester. (either analog or digital)
1 If it was kept on for 12 hours or
longer as specified.
2 It was kept on for less than the
specified period.
1 The compressor stops and the
same error code is displayed.
1 The Inverter stops and the same
error code is displayed.
2 If the inverter’s output voltage is
output with good balance, *1.
3 If the balance in the inverter’s
output voltage is not good or if the
inverter’s output voltages are all 0 V
(a digital tester cannot be used) *1.
Go to [2].
Go to [2] after keeping the power on for the
specified time.
Perform the check of wiring shown in the
explanation of each error code.
Check the IPM is faulty. (Go to “Individual
Parts Failure Judgment Methods.”)
Check the coil resistance and insulation
resistance of the compressor, and if it is
normal, run it again, and if the trouble occurs
again, replace the compressor.
* Insulation resistance : 2MΩ or more
Coil resistance : 0.359 ~ 0.716Ω
Check the IPM.
Judge that the IPM is faulty. (Go to “Indi-
vidual Parts Failure Judgment Methods.”)
If the IPM is normal, replace the G/A board,
then perform this item again with SW1-1 ON.
If the problem is not solved, replace the INV board.
If the problem is solved and you connect the
compressor again, turn SW1-1 OFF again.
Check the compressor’s coil resistance and
insulation resistance.
How many hours was the
power kept on before
operation?
When it is restarted, does
the trouble reappear?
Run the outdoor unit with
the wiring to the compressor
disconnected. At this time,
change SW1-1 on the INV
board to ON.
Note) The terminals of the 3
disconnected wires should
be isolated from each other.
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