Originally Posted by mopariac
Sounds like the switch was in the on position and the water pressure was built up so the pump turned off automatically. But after the tank was emptied and it was winterized, the pump eventually lost its prime and automatically turned back on and kept running because there was no longer any water to pump. Glad it didn't burn the pump up or worse. Sounds like a lesson learned.
If the techs who winterized your Airstream left air pressure in the H20 lines, you wouldn't know the switch was on.
As the pressure bled off, the pump kicked in. AIr pressure or water pressure, the pump won't know the difference.
On a separate but related issue, if you haven't replaced the original Univolt with a modern converter/charger (like the Iota DLS-55), you will need to check the water level in your batteries every 30 days that you stay connected to shore power.