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How to Identify Common, Start & Run Terminals on a Refrigerator Compressor

Max Stout

When preparing for the troubleshooting or testing of refrigerator compressor circuits, the identification of the common, start and run wiring terminals is of utmost importance.


The colors for the individual wires are usually as follows: black for common, yellow for start and red for run. Some refrigerators use a pin-type plug-in receptacle for compressor connections. Identify the pins by the following letters: “C” for common, “S” for start and “R” for run.


Capacitors used for starting compressor motors may have stored voltage in them, even when the appliance is disconnected. Observe all the appliance manufacturer’s safety recommendations in the owner’s manual and other servicing notifications before any work is performed.

Manufacturers usually color-code compressor terminal wiring in their products, but if a schematic is not available to cross-reference the colors, they can be identified by their location on the compressor terminal bus. You can identify and verify the common, start and run wires with basic do-it-your skills and a screwdriver.

  1. Remove the refrigerator electrical plug from its outlet.

  2. Remove the compressor access panel screws, using a Phillips screwdriver. The panel is located at the lower rear of the appliance.

  3. Locate the compressor terminal bus. The bus has several wires of various colors connected to it. Typically, the common terminal is on the top of the bus, the run is on the right-hand side and the start terminal is on the left.