What was found
COCKPIT PAC TEMPERATURE WAS UNCONTROLLABLE WHILE ON THE GROUND. COCKPIT FILLED WITH BLUEISH WHITE SMOKE BEFORE COCKPIT PAC WAS SECURED. COCKPIT SUPPLY TEMP INDICATED 234 BEFORE PAC WAS SECURED. INSPECTION OF PAC OIL SIGHT CUP INDICATES BLACK OIL. INSPECTED COCKPIT PAC OIL BOWL AND OIL WAS DISCOLORED. OPERATED APU AND INSPECTED PAC FOR ROTATION. PAC ROTATED AT 1/4 SPEED FOR 20 SECONDS AND SEIZED UP. PLACED COCKPIT PAC TURBINE ON ORDER. REMOVED FWD & AFT ACM EXHAUST DUCTS. REMOVED ACM. INSTALLED REPAIRED UNIT. INSTALLED FWD AND AFT EXHAUST DUCTS. OPS CHECKED GOOD LEAK CHECKED GOOD IAW MM 21-51-00.