Toshiba MMU-AP0091H How to check inverter output, How to check resistance of compressor winding

Cautions when servicing for compressor

1. Removing wires of both compressors check output of the inverter as described below.

How to check inverter output

1.Turn off the power supply.

2.Remove the compressor lead cables from the compressors. (Be sure to remove lead cables of both compressors.)

3.Turn on the power supply and start cooling or heating operation.

In this time, pay attention to touch the fasten receptacle terminal lug of the compressor leads so that they do not contact with other fasten receptacle terminal lug or other position (unit cabinet, etc.).

4.Check output voltage of compressor lead cable at inverter side.

When the output voltage does not satisfy the criteria in the following table, replace IPDU P.C. board.

No.	Measured position	Criteria
1	Between Red and White	400 V to 650 V
2	Between White and Black	400 V to 650 V
3	Between Black and Red	400 V to 650 V

∗After checking the output, when connecting the compressor lead again to the compressor terminal, check surely there is no distortion on the fasten terminal lug. If it is loosened, caulk it with pinchers, etc and then connect lead to the terminal.

How to check resistance of compressor winding

1.Turn off the power supply.

2.Remove the compressor lead cables from the compressors.

In each compressor, check the winding resistance between phases and resistance of the outdoor cabinet using a tester.

•Is not it earthed?

→Normal if 10MΩ or more are measured

•Is not shorted between windings?

→Normal if 0.7Ω to 0.9Ω are measured (Use a precise digital tester.)

How to check the outdoor fan motor

1.Turn off the power supply.

2.Take off three connectors (U.V.W) from the fan IPDU P.C. board.

3.Turn the fan with hands. If the fan does not turn, it is a fan motor error (Lock). Replace the fan motor.

If the fan turns, measure the winding resistance between the phases of the connector (Motor winding) with a tester. If 13 to 33Ω are measured, it is normal. (Use a digital tester.)

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