Question about Mitsubishi Mr. Slim MXZ30TN Air Conditioner

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Mistsu ductless unit compressor began running in reverse after a "technician" replaced a valve, recharged, and restarted. Follow up visit from "Technician" revealed that he had grounded a sensor when re-assembling the unit. Is it possible this caused the reversal? Appears compressor is now trash.

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  • pompman Mar 15, 2011

    THANKS ...... it appears you've verified my belief that the compressor failure was caused by the grounding of the sensor by the technician. Appreciate your help.




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This must be a 3 phase compressor.If one of the 3 hot wires is reversed to the compressor,then yes it can make the unit run in reverse.

What will happen is that any oil will be taken out of the compressor and forced into the system causing the compressor to burn up.
Another possibility is if one hot wire went to ground this would cause something called single phasing.Say the compressor needs 220 volts to run and you take half of that away,leaving it with 120 volts.The compressor will draw more amps and burn up.

What i dont understand is there should be fuses and pressure switches to protect the compressor from damage.
So yes it is possible if a sensor went to ground to do serious damage.

Posted on Mar 15, 2011


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