Bongo Fury

Whe ever I plug in the electric hook up I get a sound of a fan coming on by where the hook up is (back right of the van). This keeps going for about 10 seconds and then stops before starting again moments later and only stops when I disconnect the hookup. Any ideas and could it be dangerous? Thanks

Chiller box/fridge?

Does your hook up unit include a battery charger as some of them have cooling fans