What was found
PRIOR TO TAXI OFF, WITH ECS ON, NOTICED BURNING SMELL AND SLIGHT SMOKE IN THE COCKPIT AND CABIN. RETURNED TO RAMP AND SHUTDOWN AIRCRAFT. MAINTENANCE REPLACED THE FORWARD AND AFT CABIN EVAPORATOR BLOWER/FAN ASSEMBLY. OPS OK. AIRCRAFT WAS RETURNED TO SERVICE. FWD BLOWER ASSY OFF: P/N 300-0267-1, SN TM26307. AFT BLOWER ASSY OFF: 300-0271-1, SN K31945