As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4389 THE CREW REPORTED THE NR 1 PACK WAS UNABLE TO CONTROL BECAUSE IT WOULD GO FULL HOT TO FULL COLD AIR WITH HUMID SMELL. THE AIRCRAFT WAS REMOVED FROM SERVICE. PERFORMED OPERATIONAL TEST OF BOTH PACK 1 AND PACK 2 IAW EMB 140 AMM 21-60-00. THE OPERATIONAL TEST WAS DONE IN MANUAL AND AUTO ON DIFFERENT TEMP SETTINGS. THE OPERATIONAL CHECK WAS GOOD. NO DEFECTS NOTED. THE AIRCRAFT WAS RETURNED TO SERVICE.