2001 Ford Taurus SES, Added Coolant and it all leaked out, now my serpentine belt is squealing, heater wont work and thermostat is going really high.

Need to find out where the leak is. Do a pressure test on the coolant system. This will help locate the leak. Without coolant in the system you will not have heat and heater will blow cold air. Is white smoke coming out of the exhaust? If so I suspect a blown head gasket. Do you live up north and experiencing freezing temps? If so did you have enough anti freeze in system? If not could have any number of things leaking.(cracked head, cracked block, freeze plugs, ect.)

Belt could be squealing due to coolant leaking on it. Inspect engine for leak.

Where can I do a pressure check at? It seems to be coming from the reservour and not the radiator but Im not 100% positive. Theres no white smoke and it never gets below 50 where I am. it was empty before I put the coolant in and the heater and ac worked perfectly before.

Did you bleed all the air out of the cooling system when you added the coolant? If not you will need to do this for system to operate properly. Local auto parts stores will loan you the items to pressure test the cooling system. What this does is it pressurizes the cooling system and forces it to leak so that you can locate the leak.

No we didnt bleed it, I started working at Jiffy Lube and they just topped it off for me. I guess its off to Auto Zone.

Coolant blowing out the reservoir could mean blown head gasket. What color is your oil? Does it look like motor oil or a milkshake?

I prefer using them also. They can show you how to bleed the system and also how to use the pressure test items. I would not advise driving it much with it overheating. Could cause more damage.

its still pretty golden looking, I checked that as soon as someone told me to.