As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - ON FLIGHT 2190, RETURNED TO GATE. RECURRING C/B CABIN TEMP MANUAL POPPED AFTER ENGINE START. THIS C/B IS POPPING WHEN ONLY THE NR 2 BLEED IS ON. C/B POPPED AFTER NR 1 ENGINE START EACH TIME. MAINTENANCE REMOVED AND REPLACED 2161 -K16 RELAY. FUNCTIONAL TEST GOOD, SYSTEM WORKS NORMAL IN AUTO AND MANUAL. AIRCRAFT RETURNED TO SERVICE.