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Points to Note When Servicing Compressor
(1) When checking the outputs of inverters, remove the wiring from all the compressors.
How to Check Inverter Output
(1) Turn off the power supply.
(2) Remove compressor leads from the IPDU P.C. board (A3-IPDU). (Be sure to remove all the leads.)
(3) Turn on the power supply and start cooling or heating operation.
Be careful not to make simultaneous contact with two or more faston connectors for compressor leads or a
faston connector and some other object (e.g. the unit cabinet).
(4) Check the output voltage across each pair of inverter-side (CN703, 704, 705).
If the result is unsatisfactory according to the judgment criteria given in the table below, replace the IPDU P.C.
board.
* When connecting the compressor leads back to the compressor terminals after checking the output, check the
faston connectors thoroughly to ensure that they are not crooked. If there is any loose connector, tighten it with
a pair of pliers, etc. before connecting the lead.
How to Check Resistance of Compressor Winding
(1) Turn off the power supply.
(2) Remove compressor leads from the compressors.
(3) With each compressor, check the phase-to-phase winding resistances and winding-to-outdoor cabinet
resistance using a multimeter.
• Earth fault?
It is normal if the winding-to-outdoor cabinet resistance is 10M or more.
• Inter-winding short circuit?
It is normal if the phase-to-phase resistances are in the 0.6-1.0 range. (Use a digital multimeter.)
How to Check Outdoor Fan Motor
(1) Turn off the power supply.
(2) Remove fan motor leads from the IPDU P.C. board for the outdoor fan (CN703-CN705).
(3) Rotate the fan by hand. If the fan does not turn, the fan motor is faulty (locked up). Replace the fan motor.
If the fan turns, measure the phase-to-phase winding resistances using a multimeter. It is normal if the
measurements are in the 1.14-1.70
range. (Use a digital multimeter.)
No. Measured leads Criterion
1 Red-White 380~580V
2 White-Black 380~580V
3 Black-Red 380~580V
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