B767-200
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
While climbing through FL230 the Left AC Pack INOP light came on then the Left Pack Temp EICAS message came on. We followed the QRH procedures and shut down the left AC pack. When level at FL340 we then got a Cabin Auto Inop warning on the pressurization controller. We were on the #2 and switched to the #1 but still had an inoperative light. An EICAS message showed auto 1 and auto 2 pressurization systems inoperative.We followed the QRH procedure and attempted to get control of the cabin pressurization system through use of the manual system. The outflow valve was full closed and cabin was still climbing at approximately 500 FPM. When the cabin got to around 8;000 FT and after a conversation with our Dispatcher and Maintenance Control we decided to return to our departure airport. We received ATC clearance and started a slow descent because every time we brought the throttles to idle the cabin started to climb at around 500 FPM or more. With the thrust slightly up the cabin stayed at 0 FPM. It wasn't until we were below 12;000 that we were able to get the cabin to start to descend. During approach and landing we were unable to get the outflow valve to move at all in the manual position and could not depressurize the aircraft as the procedure indicated. On the ground and clear of the runway we shut down the right AC pack and the cabin started to return to field elevation. Prior to parking we opened the First Officer's cockpit window to ensure the aircraft was depressurized prior to anyone attempting to open a door.
A B767 flight crew returned to their departure airport when they lost control of the pressurization system.