Windshield Wiper Fluid Engages

92 Geo Metro Convertible, 5 spd, 3-cylinder.

Bought Wednesday. Driving in storm on Friday. As the windshield wipers were running, the windshield fluid would engage without me doing anything. It would stop when I'd turn the wipers off. I seemed to recall that it never did it while I had the wipers on high.

Any suggestions?

Thanks.