Fan only blows on high

The fan blows only on high because the variable speed resistor in the dash has burned out. Water sound in the dash could be air bubbles in the coolant flowing through the heater core located in the heater box under the dash, passenger side. Top up radiator coolant and overflow bottle.

It may also go by the name resistor pack, it's a common fault when the blower motor only works on high. Any auto parts store should be able to look the part up and show you where it installs. You only need basic tools like a screwdriver. YT videos can also help you DIY.