What could be wrong with my car it's overheating. on 1998 Lincoln Continental

I have replaced the radiator and thermostat. I haven't lost any coolant My levels have remained the same. What could be the issue

Asked by for the 1998 Lincoln Continental
There could be a blockage in the system or the water pump is no longer working or the cooling fan is not working. Seek mech. for a diagnostic and est.
All my fans are working and the check engine light has not come on.