What was found
(CAN) DURING CLIMBOUT, CREW REPORTED A BURNING TYPE ODOR, NO VISIBLE SIGN OF SMOKE. THEY ALSO REPORTED THE NR 1 PACK COULD NOT BE CONTROLLED IN AUTO OR MANUAL MODE. THE NR 2 PACK WAS ALREADY UNDER MEL. FLIGHT RETURNED AND LANDED WITHOUT FURTHER INCIDENT. DURING ACFT RUNS AT HANGER WE NOTED THAT THE NR 1 PACK WAS ABLE TO CONTROL IN AUTO AND MANUAL TO BOTH HOT AND COLD TEMPS. NR 2 ACM FOUND SEIZED. NR 2 ACM REPLACED. ACM FUNCTION AND LEAK CHECKED SERVICABLE.