What was found
ODOR DURING LEVEL CRUISE AT FL 350. BEGAN TO DETECT A HOT PLASTIC ODOR IN THE COCKPIT. AFTER 5 MORE MINUTES ODOR INCREASED. NO SMOKE OR VAPOR AT ANY TIME. REVEIWED 2018-F0001 TR E190 ODOR RECOGNITION. F1 AND F2 REPORTED SAME ODOR AFTER ABOUT 15 MINUTES. CREW USED PROCEDURE TO ISOLATE TO THE NR 2 PACK. ODOR IN COCKPIT DIMINISHED FIRST, FOLLOWED BY FRONT OF CABIN AFTER APPROXIMATELY 10 MORE MINUTES. SLIGHT ODOR PRESENCE REMAINING. BOTH PILOTS DONNED OXYGEN MASKS TO REDUCE ACCLIMATION. AIR CONDITIONING PACKS - SINGLE ); REMOVED AND REPLACED NR 2 PACK ACM IAW AMM 21-51-05. MX 4 UPDQTED PLACARD REMOVED AND MCC NOTIFIED. INSPECTED NR 2 PACK HEAT EXCHANGER AND FOUND TO BE OK FOR SERVICE IAW AMM 21-51-04.