As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, AIRCRAFT WOULD NOT PRESSURIZE OVER 4 AT 14,000 FT IN AUTO OR MANUAL. ACCOMPLISHED AIR TURNBACK TO LCK AND LANDED WITHOUT INCIDENT. FOUND PRESSURE CONTROLLER DEFECTIVE. REPLACED CONTROLLER, SYSTEM OPS CHECKED GOOD PER MM CH 21.