As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1736 SJU-FLL, CREW DECLARED EMERGENCY AND AIRCRAFT RETURN TO SJU DUE TO VISIBLE SMOKE IN COCKPIT AND CABIN DURING CLIMBOUT. SMOKE OF SOURCE COULD NOT BE IDENTIFIED. PERFORMED SMOKE AND ABNORMAL SMELL IN CABIN AND COCKPIT CHECK IAW FIM 21-20-00-810-801A FOUND ACM AT FAULT. WHEN PACK NR 1 IS SWITCHED ON, BURN SMELL FILLS THE COCKPIT. REMOVED AND REPLACED PACK NR 1 ACM AS PER AMM 21-51-05. OPS CHECK PER AMM 21-51-00-710-801-A500 ALL PARAMETERS OK.