What was found
MSP - FLT 707 - RETURNED TO GATE, NO EMERGENCY DECLARED. AFTER STARTING NR 1 ENGINE AND TURNING THE RIGHT PACK ON, THE MAIN CABIN FILLED UP WITH AN ODORLESS HAZE. DEFERRED RIGHT A/C PACK PER MEL 21-1. DISCONNECTED RT PACK CANNON PLUG, D492, AND SLOWED. RIGHT PACK DEACTIVATED, CLOSED RIGHT PACK AIRCONDITIONING BAY DOOR. (M)