What was found
PERFORMED AN AIR TURN BACK DUE TO BOTH AUTO 1 AND AUTO 2, PRESSURE CONTROLLERS FAILED AFTER TAKEOFF. UNABLE TO REGAIN CONTROL OF PRESSURIZATION USING MANUAL MODE. REACTED BACKWARDS TO WHEEL CONTROLS INPUT. BITE CHECK OF BOTH AUTO PRESSURE CONTROLLERS SHOWS NO FAULTS. MANUAL OPERATION IS SMOOTH AND VALVE FOLLOWS POSITION OF CONTROL WHEEL. TROUBLESHOT IAW FIM. NO TROUBLE FOUND. ALSO, PERFORMED OPERATION TEST OF OUTFLOW VALVE IAW AMM. OPERATION CHECKS GOOD. REPLACED AUTO MANUAL CONTROL SWITCH, S1-154 AND CABIN TRANSFER RELAY R2-258 PRECAUTIONARY.