As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DEPARTURE FROM MKE CABIN ENVIRONMENTAL CONTROL VALVES DROVE TO FULL HOT POSITION. CREW COULD NOT CONTROL IN AUTO OR MANUAL. AIRCRAFT RETURNED TO MKE. TROUBLESHOOTING BY STERLING MAINTENANCE FOUND WIRE BROKEN AT TEMPERATURE LOW LIMIT SENSOR. REPAIRED BROKEN WIRE. OPERATIONS CHECKED GOOD.