Electric Power & Utilities/condenser fan motor testing

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Question
found my 230v heat pump condenser fan running,but very slowly. I checked the motor winding resistance and found normal reading, about 50ohms with no grounds. When I turned the fan motor by hand, the ohm reading would fluctuate. Is this a bad spot in the windings or is that normal?

Answer
A ohm test is only accurate if you know the original values from the factory. In our shop the only test we performed where a bearing, (movement up and down in the vertical plane) insulation (ground) and voltage/amperage test. Failure of any test, and the motor was scrapped. It is not economical to repair these motors. Before I did anything, I would check the motor running capacitor.  

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Charles C. Jones

Expertise

Let Me help you with your problems with single phase and three phase electric motors. I can tell you how to troubleshoot your motor problems. From simple testing of capacitors, how to test your windings, replacing bearings, and general maintenance. Before we go any further, remember these words of advice: Disconnect the power before you do anything! Please limit your questions to electric motors and there immediate components. I review each question, and if I can answer or help, then I will. If you receive a rejection, it means it is out of my expertise, and just do not have the answer. I'll be waiting for your question.

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I have 40 years experience in the repair of electric motors and related equipment. I am a master machinist in the field of motor repair. I was employed with my company for 35 years, but retired in May of 2013. The downside to that is I lost access to a lot of technical data. I will still try to give you the most accurate advice that I can.

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Former member EASA

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