How to figure out why my car is overheating

have you checked your coolant level?

Yes, the coolant is full. I also changed out the thermostat, so had to flush the coolant for that.

when you flushed the coolant, did you turn the heat on? that way the coolant can run throught the heater core

Have you had it checked for leaks? Like the coolant hoses, crossover tubing that's underneath. If it's just blowing cool air and no heat, it's likely the switch that controls ac/heat. The cable inside the dash comes loose from its bracket, and when you turn the knob, the cable isn't actually moving to go from ac to heat. You have to take the dash off, starting from the left of the steering column, and work your way across, removing each switch mechanism and screws. This is fairly simple, but I ran into a problem with reaching 2 screws that hold the dash on, and they are located at the bottom side, and you can't get to them unless you remove the entire console frame and radio. Fixing the cable is the easy part. You simply loosen the clamp screw, move the cable back into position on the clamp, and retighten the screw. It's getting the dash frame apart to get to the cable apparatus. Good Luck. There is a video you can watch online where the mechanic performs this entire "fix", but he didn't tell about those 2 screws you can't get to! But watching that video will show you exactly how to do it all. Very helpful!!