My 71 semi-camperized bus has, among other accessories installed by an
unknown PO, a unit called a Pla-Cool that sticks up out of the otherwise
stock roof. It's a white, rounded, heavy-duty plastic sort of cowling
affair, about 6" tall and maybe a foot square. I think it might be a
circulating water air-cooler, but I really have no clue.

Controls are mounted on the bottom half of the unit, which protrudes
downwards from the bus ceiling. It has on/off switches for "fan" and "pump"
and another switch that flips it from "cool" to "exhaust."

It sat unused for years until one day I noticed, tucked back in right rear
corner of the engine compt. above the battery, an empty fuse holder. I
popped a 15 amp fuse in, went into the bus and turned the Pla-Cool on, and
the fan began to whirr. Paranoid of a possible VW electrical debacle, I
turned it off, took the fuse out and haven't touched it since. 

But I'm curious. Anyone have experience with these things? Does it circulate
water (that intriguing "pump" switch)? If so, where do you put the water in?
What amp fuse should it take? Would I be inviting disaster to use it?

Thanks for any knowledge or even speculation.

-steve tokar