With both engine bleeds on, there is only pressure in the R duct. The L duct is indicating near zero. Both packs were operating, and cycling the isolation valve and packs had no effect on the pressure. Cabin is pressurizing fine.So, what happened to the bleed air?

Looks like a corrupt panel state.I'm assuming you've already started both engines.

APU on ? Also isolation valve should be ON if APU bleed is available...

Looks like a corrupt panel state.I'm assuming you've already started both engines.

Yea I guess so. It was fine the next flight. I just wanted to make sure that it's the panel, not an actual operator's error ;)

APU on ? Also isolation valve should be ON if APU bleed is available...

APU off. This was taken at some 38000 ft.

Write it off as corrupt panel state has happend to me twice before and then was fine the next time.

APU is off.Looks like a corrupt panel state to me, too.

I agree with Kyle, probably a corrupted or old panel state. There is no bleed trip off, if engines are working and no failures are present, there must be pressure.Just to troubleshot more, turn on the APU and see if it supplies pressure on the left duct.ISOL valve in that configuration (auto)s closed as all bleeds and packs are on. APU will not affect the isol. valve position, and, as the APU supplies pressure to the left side, the closed position is preferred to let the 2 systems, l and r, to be independent.Are you sure the pack is working? Have you tried to shut down the rh one and see what happens to the pressurization?

I agree with Kyle, probably a corrupted or old panel state. There is no bleed trip off, if engines are working and no failures are present, there must be pressure.Just to troubleshot more, turn on the APU and see if it supplies pressure on the left duct.ISOL valve in that configuration (auto)s closed as all bleeds and packs are on. APU will not affect the isol. valve position, and, as the APU supplies pressure to the left side, the closed position is preferred to let the 2 systems, l and r, to be independent.Are you sure the pack is working? Have you tried to shut down the rh one and see what happens to the pressurization?

Yep. I cycled the L and R packs independently. No major changes to the duct pressure.

Good luck starting the APU at 38000 feet, mate.Frank Cooper

Don't wanna be THAT GUY Frank, but just so you know, the APU's very capable of starting up at the 73's service limit of FL410. :(

Good luck starting the APU at 38000 feet, mate.Frank Cooper

There's no APU start limit, only operational limits :(

And with that, it will support electrical power up to 410. Admittedly, that is not the case with air pressure..

Good luck starting the APU at 38000 feet, mate.Frank Cooper

If he want to use the APU to troubleshoot, he is not forced to stay at fl380... He can descend to fl170 and below.It is just for testing. Noone will shot him if will not follow the crz altitude.It is also the only way to find if the problem is related to the bleed logic or the pneumatic distribution.

Yep. I cycled the L and R packs independently. No major changes to the duct pressure.

You will see difference only in cabin pressurization with both packs off. No difference in duct pressure when powered by engines (depending on thrust).