Now check to see if the Compressor is grounded. Set up the meter to read Ohm's. Hold one lead on one of the copper lines attached to the compressor. Use the other lead to go to each of the compressor terminals Record the results. Common to Ground Start to Ground Run to Ground Explain the measurements and the condition of the compressor motor using correct trade terminology: Rewire the compressor, close up the unit and return any tools to the proper location. Single Phase Compressor Trainer. Locate the iConnect TU-521 Single Phase Compressor Trainer