1997 Volkswagen Van Temperature Warning light

The coolant warning light keeps flashing even though the coolant level is barely below the minimum level. Is the coolant level indicator that sensitive?

second question. This is a Winnebago modified VW Eurovan. There is a warning buzzer that keeps going off which we cannot find, not do we know what it is buzzing for. It seems to be directly above and to the right of the driver's head, not in the pop-up unit, but directly infront of it. The buzzer stops buzzing when the van is running, and starts soon after it is turned off. It sounds about every 45 seconds. What gives?