Jeep gran Cherokee 1997 Radiator

When we open the radiator cap it seems like there is no fluid but once the car gets a like bit hot and we open the cap there is fluid. The fluid reservoir sometimes gets empty quickly but not often. We have no lights in dash board telling us that there is something wrong. What do we do?

Fill the radiator. And stop opening it when the car is hot - that’s a really good way to end up in the hospital with severe burns.