Hyundai Repair: 2001 Hyundai Elantra, coolant leaks, hyundai elantra

Question
The heater fan blows, but no heat comes out (cold air) and then the vehicle started to overheat - is this a stuck thermostat?  

Answer
It's got all the characteristics of a stuck thermostat or low coolant.

First check your coolant level, both in the reservoir and the radiator (with engine cool).  If they're not full, you should check for coolant leaks.

If you've got no leaks, then you should check to see if you have coolant flow when the engine reaches operating temperature.  If not, then you probably need a thermostat.