Heat Sink of VVVF Unit Getting Hot

You will have to quantify the term "hot". heat sinks are, by definition, a place for heat to go!

But if I assume you know how hot it MIGHT be under normal operating conditions (typically 70C) and it is hotter than that, then there is a big clue to your situation here:

"Out put disconnected from field motor problem continue.

Out put cable removed from module, heating stopped."

If I interpret your translation correctly, you disconnected the motor lead cables at the motor end and the heat sinks remained hot. But when you disconnected them at the drive end, the problem went away. This would immediately lead me to believe you have an insulation failure in the cables somewhere between the drive and the motor. Under circumstances other than a VFD, this would be picked up by the Short Circuit Protective Device (fuse or circuit breaker) and the circuit would be disconnected. But when you have a VFD in the circuit, it has its own ability to artificially limit the current in the circuit. So if it is a highe resistance fault, such as deteriorating insulation on the cable or a very small nick, the VFD is pumping current into that fault at the limit level it is programmed for and does not trip. Eventually that fault will worsen and the VFD will not longer be able to limit it, or the VFD transistors will fail.

The first thing I would do is to disconnect the leads at both ends and do a megger test on them, both phase-to-earth and phase-to-phase. If you don't know what that means, hire a professional who does. This is not something to be taken lightly.