As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THAT WHILE ON TAXI THE NR1 BLEED OVERHEATED AND AT THE SAME TIME THE CREW DETECTED A SLIGHT ODOR OF FUMES ENTER THE COCKPIT. THE FUMES QUICKLY DISAPATED WHEN THE NR1 PACK AND NR1 BLEED WERE TURNED OFF. THE ACFT WAS REMOVED FROM SERVICE. REPLACED THE OVER TEMPERATURE SWITCH ON THE LT SIDE IAW JIC 36-11-61. THE GROUND RUN-UP WAS FOUND TO BE WORKING PROPERLY. THE ACFT WAS RETURNED TO SERVICE.