B737 flight crew reported during climb that the Captain suspected an issue with the pneumatic system. They reset the pack switches and noticed a small change in the airflow but were unsure if they fixed anything.
Synopsis
B737 flight crew reported during climb that the Captain suspected an issue with the pneumatic system. They reset the pack switches and noticed a small change in the airflow but were unsure if they fixed anything.
Narrative
While climbing on departure out of ZZZ; the Captain said he suspected an issue with the aircraft pneumatic system. Climbing through around 15;000 ft MSL; we received an automatic ACARS printout relaying an issue with switch position and actual operation of the pneumatics. Switches were: L Pack AUTO; ISOL (Isolation) Valve AUTO; R Pack AUTO. Actual operation showed on the printout: L Pack OFF; ISOL Valve AUTO; R Pack HIGH. We requested an intermediate level off at around 17;000 ft MSL to look at the issue. We determined there was no procedure in the FM's (Flight Manual) non-normal section related to this situation. One at a time; we turned off each pack and returned the switch to AUTO. Following left pack reset; we noticed an increase in airflow in the flight deck showing left pack returning to the AUTO operating mode. We then requested to continue climb to cruise altitude and completed the rest of the flight uneventfully.Following pushback at ZZZ; we were notified of a departure delay; with control time 45 mins away. Ground control sent us to the inactive runway to wait. We single engine taxied to the hold area; shut down the #2 engine; and turned on the APU bleed air; and opened the ISOL valve. With the passenger cabin temperature rising. I turned the R pack to HIGH and L pack to OFF. Shortly before departure control time; we started both engines per normal procedures; with both packs OFF. During after start flow; both packs switches were placed in AUTO; with ISOL valve in AUTO as well. Shortly before takeoff; I noticed the N1 Takeoff settings in the FMC were slightly different between engines 1 and 2; but did not at the time understand that could be an indicator of the two packs operating at different settings.I received a FOQA debrief about this event regarding the data provided by the aircraft during the flight.
Second reporter narrative
EDCT (Estimated Departure Clearance Time) issued on taxi out; parked and shut down engines. Configured bleed panel for left pack OFF and right pack HIGH for max passenger cooling. Started engines; configured panel; ran checklist and took off...While setting power I glanced at FOs N1 page to see the power setting and after a few seconds I noticed the settings were 95.0/95.8. It took me a couple more seconds to see the difference as the 8 and 0 look similar. I immediately glanced up to the anti-ice and AC panel to look for an improper switch position that would be causing the mismatch. ALL SWITCHES WERE IN THEIR PROPER TAKEOFF POSITION. At this point; we were nearing or past 100k and there was obviously no reason to discontinue the takeoff.The ZZZ SID can be a high workload procedure so I informed the FO something wasn't right with the bleed panel but we would continue to fly the plane and diagnose further when the AP (Autopilot) was on. At this point there was NO indication anything was wrong with the airplane since the N1 page disappears after takeoff; we were pressurizing normally and we don't have any sort of synoptic page. I did notice a trivial split between bleed pressure from engine 1/2 but this is quite common on our fleet.Once out of the terminal area with AP on; we requested a level off to diagnose 'problem'. We attempted to reference the FM (Flight Manual) but because we had no abnormal indications; there was nothing to reference. At this point we noticed the printer had printed a report of an incorrect bleed configuration for takeoff. We referenced it and it showed we had the left pack OFF and right pack HIGH. We again looked at the panel (as I did at least 10 times already) and decided that the packs are somehow still operating in the configuration we had on the ground during the delay and not operating according to their switch position.We recycled both packs individually and perhaps felt a small change in airflow and the bleed needles appeared to be more aligned. We still had no idea if we 'fixed' anything or still had an incorrect bleed configuration or if we ever had one to begin with.We continued to ZZZ1 without further issues.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.