As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IMMEDIATELY AFTER TAKEOFF THE CABIN V/S WAS ERRATIC FROM -900 TO +900FPM. THE OUTFLOW VALVE FLUCTUATED ERRATICALLY FROM PARTIALLY OPEN TO A LITTLE OVER QUATER OPEN RAPIDLY AND THERE WAS A CYCLE CONSISTING OF MUCH AC AIR TO VERY LITTLE AC AIR WITH PAIN TO THE ECIS UP TO FL180.--