If the converter clutch disintegrates, it can drag like it is locked up, and send clutch material through the cooler line, and block the inlet of the radiator heat exchanger.
Fluid will not circulate and the trans will run at a higher temperature. You can check this with a thermo heat gun, or remove the lower line at the radiator and check for debris.
You can check fluid circulation-- if you remove the top line where it connects to the trans-- slip a hose on the tubing and start the engine-- should be full flow. Don't run very long, just a few seconds.