Liquid sounds in the dashboard, can anybody help?

[94rangerblue]

I have a 1994 2wd supercab ford ranger, i noticed after it rained pretty hard for 2 days straight, that when i take off in 1st gear I can hear liquid moving around in the dash, around where the dashboard meets the glass, I looked under the hood and I did not notice anything, all fluids seem to be full so I was wondering if anybody could give me some suggestions. thanks.

 

[Jason]

Sounds like the heater box drain is clogged up.