Narrative:

Shortly after being cleared to 16;000 by departure the air coming from the right side pack suddenly became extremely hot. I reverted the right pack temperature control to manual mode and full cold with no affect to the temperature. After being handed off to center we were cleared to climb to FL350 and started to notice smoke coming from the windshield defrost vents. Smoke was also coming out of the cabin air vents. Stopping the climb at 16;000 ft the captain and I donned our oxygen masks and the captain turned off the right right side pack's bleed air supplies while I notified center of the situation; that we needed to return back to our departure airport; and advised them of souls on board and fuel remaining. We were cleared direct to the airport. While troubleshooting the captain noticed that left side pack was not supplying any air and that the cabin altitude was rapidly climbing. In the turn back to the airport I notified ATC that we had also lost pressurization and were descending. Center cleared us down to 10;000 ft. In less than 1 minute from turning off the affected pack the smoke had started to clear. Following the smoke in the cabin procedure the ram air vent was opened and the emergency depressurization switch was depressed to help flush the smoke out of the cockpit and cabin. The decision was made to make an overweight landing at our departure airport in order to land the aircraft as soon as possible. L-1329 maximum landing weight is 36;000 pounds and a very smooth landing was performed by the captain at 40;000 pounds after conducting a visual approach for the runway. Once clear of the runway a normal; unassisted taxi was performed to the ramp. The aircraft is currently under inspection by our mechanic to determine the actual cause of the problem; but it is believed that the right side pack suffered a bearing failure which lead to it seizing. This resulted in the extremely hot bleed air to not be cooled before entering the cabin/cockpit ducting. This extremely hot air caused the smoke. The mechanic is currently also investigating why the left side pack was unable to maintain pressurization after the right side was shut down.

Related reports:

Google
 

Original NASA ASRS Text

Title: L1329 flight crew experiences air conditioning smoke during climb and turns off the right side bleed switches. This corrects the hot air and smoke problem but it is noticed during troubleshooting that the left pack is not supplying any air. Flight returns to departure airport where Maintenance discovers the right ACM has seized.

Narrative: Shortly after being cleared to 16;000 by Departure the air coming from the right side pack suddenly became extremely hot. I reverted the right pack temperature control to manual mode and full cold with no affect to the temperature. After being handed off to Center we were cleared to climb to FL350 and started to notice smoke coming from the windshield defrost vents. Smoke was also coming out of the cabin air vents. Stopping the climb at 16;000 FT the Captain and I donned our oxygen masks and the Captain turned off the right right side pack's bleed air supplies while I notified Center of the situation; that we needed to return back to our departure airport; and advised them of souls on board and fuel remaining. We were cleared direct to the airport. While troubleshooting the Captain noticed that left side pack was not supplying any air and that the cabin altitude was rapidly climbing. In the turn back to the airport I notified ATC that we had also lost pressurization and were descending. Center cleared us down to 10;000 FT. In less than 1 minute from turning off the affected pack the smoke had started to clear. Following the smoke in the cabin procedure the ram air vent was opened and the emergency depressurization switch was depressed to help flush the smoke out of the cockpit and cabin. The decision was made to make an overweight landing at our departure airport in order to land the aircraft as soon as possible. L-1329 maximum landing weight is 36;000 LBS and a very smooth landing was performed by the Captain at 40;000 LBS after conducting a visual approach for the runway. Once clear of the runway a normal; unassisted taxi was performed to the ramp. The aircraft is currently under inspection by our mechanic to determine the actual cause of the problem; but it is believed that the right side pack suffered a bearing failure which lead to it seizing. This resulted in the extremely hot bleed air to not be cooled before entering the cabin/cockpit ducting. This extremely hot air caused the smoke. The mechanic is currently also investigating why the left side pack was unable to maintain pressurization after the right side was shut down.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.