As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BLOWER AND FREON AIR SYS MAKES A NOTICEABLE GRINDING AND BUZZING SOUND ACCOMPANIED BY A FRICTION BURNING ODOR. IT IS MOST APPARENT AT THE AIR EXHAUST. THIS WORSENS THE LONGER IT RUNS. INSTALLED O/H MOTOR ASSY IAW CMM 21-0012, AND MM 21-51-00. LEAK & OPS CHECKED GOOD.