car is running hot and fan running constantly?

If you have no leaks and are your coolant level is proper you may have a big air bubble. The best way to make sure you don't have bubbles is to purchase or rent a coolant vacuum tool that puts the system in a vacuum and then you suck the coolant in. If you know for sure you have no air then it could be a pump, temp sensor or head gasket issue but this would require more testing. If you prefer to bring it to a shop then use this link to find one near you. https://repairpal.com/repair-shops Alex