What was found
CABIN FILLED WITH SMOKE. A/C EVACUATED ALL ELECTRICAL SWITCHES OFF. SMOKE APPEARED TO COME FROM REAR OF CABIN. SUSPECT SUPPLEMENTAL A/C. NO ENGINE RUNNING, ON EXTERNAL POWER. MAINTENANCE FOUND SUPPLEMENTAL A/C COMPRESSOR MOTOR TO BE BURNED UP. REMOVED AND REPLACED COMPRESSOR MOTOR P/N 1134104-1, S/N ON 1425, S/N OFF 480 IAW CMM 9, 2, 1. OPS CHECKS GOOD.