Overheating and no heat in car

Hi Kelley!

Before you shell out any money, there are a few things you can do to test your cooling system for free. I don't know where you are located but, places like O'Reilly and AutoZone can pressure test your coolant system for free to determine if there are any leaks that you might be missing. With the same tool, they can test your radiator cap to make sure it is up to snuff. To be clear, the employees will do that for you, free of charge. Yay!
A quick test to see if the thermostat is working, when the car is at warmed up (not screaming hot) carefully feel the upper and lower radiator hoses. They should be different temperatures. If they are the same, the thermostat has failed.
Another possibility is that the heater core is clogged. Sometimes these leak inside the car, sometimes not. It is usually located behind the glove-box. Rule out the other problems before jumping to a heater core problem.

I have included some articles on thermostats:
https://www.2carpros.com/articles/how-an-engine-thermostat-works

and coolant leak symptoms:
https://www.2carpros.com/articles/coolant-leak-symptoms

To help you have more information.

Best of luck!