What was found
DURING CLIMB, FL220, REPORTED SMOKE IN THE COCKPIT AND SMELLING ELECTRICAL SMOKE, F/A CALLED REPORTING SMOKE IN THE CABIN, CREW WENT ON OXYGEN, RAN THE QRH, AND RETURNED TO DEPARTURE AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND FOUND THE NR 1 ACM TO BE FROZEN AND DAMAGED. R & R THE NR 1 ACM, OPS TESTED WITH NO DEFECTS, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE. DISCREPANCY REPEATED. FOUND NR 1 RAM AIR VALVE ASSY WITH WORN BUSHING AND IT WAS REPLACED.