I have a volvo 2624 refridgerated truck that overheats.I had the radiator checked,replaced the water pump,replaced the thermostat and it still overheats

Any water in the oil, or oil in the water, brakes dragging?

Phosphate scale may have blocked off the passages in the radiator, which may need to be rodded or replaced:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235973

Only use a 50/50 mixture of the recommended antifreeze and distilled water.

Does it have an electric fan and is it working or if it has a shaft driven fan it could be a bad fan clutch. Remember there is always a list of things that can cause one problem you just check them all and cross them out till you find out which one is causing the problem.