some times the sloshing noise its air in the heater core and the sound is from that, if your drains were plugged up your floor would be getting wet.
so does the heat work?
what you can do it your heat sucks or no heat, is take the 2 hoses off the alt bracket, and run a garden hose through one of them, it matters not witch one you put the hose on. if you get a big air pocket first before coolant comes out you had air, top off both hoses and put back on the alt bracket.
then let the car idle with the rad cap off till the fans turn on, and with the a/c off. then bleed the t stat housing, top off the rad and cap it.
you have a bleeder screw on top of the thermostat, open it up till a stream of coolant comes out, then snug it back up.
