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Compressor wiring

Turn off the power. Disconnect the compressor wires. Using an ohmeter, ohm out the 3 comp. terminals. Unless the windings are shorted or grounded or otherwise damaged, the highest ohm reading between any two terminals is start to run. The next highest will be common to start, with the smallest reading common to run. The run cap gets wired between start and run. The Copeland Electrical Handbook has the information you're looking for. Also Techumseh and Bristol Compressors have good information available.


  • Barrington White
    Barrington White Member Posts: 37
    Compressor wiring

    I'm trying to understand the wiring of the compressors. I was doing a compressor change out and the terminals for the wiring were burnt off. From my understanding I know that the common winding is connected to the run capacitor. Does is matter which side of the contactor is feeding the capacitor or does it matter depending or which winding it is feeding weather it also is the run or the start winding.

    I usually work on Carrier units so they come with a plug that you can only attach one way. So I never gave it much thought
  • Empire_2
    Empire_2 Member Posts: 2,343
    Hope this helps

    Here are a few wiring set up. This info should also be on the schematic if you can still read it. Often times it fades away or is gone....Good luck

    Mike T.
  • Techman
    Techman Member Posts: 2,144

    Comp windings-typically,usually,most times,quiet often,BUT NOT 100% OF THE TIME;the c-s-r is read like a book ,from left to right,from the top line then down to the next line.IF the run cap is used as a crankheater then it MUST be wired from the line side of the contactor;all other times the cap is wired from the load side of the contactor.Not ALL Carrier comps have that easy to use plug so understanding the caps is a must
  • Techman
    Techman Member Posts: 2,144

    Both the start cap and the run cap are in the START winding.NO caps in the run winding!
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