What was found
FLT 3038 - ON CLIMB-OUT FROM MSP, THE CREW REPORTED THAT THERE WAS NO AIR FLOW FROM THE BLEED AIR SYSTEM AFTER IT WAS SELECTED. THE AIRCRAFT RETURNED TO MSP. MAINTENANCE WAS UNABLE TO DUPLICATE THE DISCREPANCY. UPON FURTHER INVESTIGATION, THE WATER METH QTY WAS AT ZERO. MAINTENANCE SUSPECTS THAT THE WATER METH SWITCH WAS ON, THUS CUTTING OUT THE BLEED AIR SYSTEM. ALL CHECKS SATISFACTORY. (M)