737 Pack switches at the gate ???
So you are at the gate, APU is off and there is no conditioned air connected.
You are doing a 40 minute turn and don't plan on using any air until you start the APU about 5 prior to push time.
Had another pilot tell me that he was told to turn the PACK switches to off in that scenario as it would "burn up the fans".
Now, I have always left the packs in AUTO until ready to start engines. Couldn't find anything in our books either as to where the switches were supposed to go. The only reference was to turn them off if conditioned air is connected at the gate.
I haven't talked to our Mx department yet, but as far as I know, the pack switch just moves the pack valve, or lets it.
The pilot insisted that it also turns on the fan that draws air over the packs and he could hear that when doing the walk-around.
I say that fan comes on when the pack is operation only and it does not matter where the Pack switch is at the gate with nothing running?
Any ideas or explanation?