As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATC REPORTED ONLY PRIMARY ON THE L XPDR SWAPPED TO R NO CHANGED AC RETURENED TO GATE AND MAINTENANCE GROUNDED AC. MAITENANCE PERFORMED ATC TEST IAW B767 AMM 34-53-01 NO FAULT FOUND TEST PASSED AC REMAIN CAT IIIB. AND RETURND AC TO SERVICE . AND AC DEPARTED .