As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER COMPLETING PATIENT TRANSFER & APPROX 10 MINUTES FROM BASE, ACFT AC UNIT WAS TURNED ON. IMMEDIATELY A PECULIAR SMELL WAS NOTICED BY CREW, IN THE AFT CABIN. AC UNIT WAS TURNED OFF & THE SMELL STOPPED. LANDED AT BASE & NOTIFIED MECHANIC.