There is no fuse that would shut down the heater without effecting the power seat operation. The seat bottom and back heater are separate elements. However, because the temp sensor is in the bottom only, if either heater element burns out, the entire seat will not heat up.
Do you have a scan tool that can communicate with driver seat module. You will be able to determine is the module is receiving a signal from the switch.
There is a good troubleshooting chart for seat heater inoperable in service manual. It is based on having a scan tool.
I think i provided copies of this chart in another thread. I can repost IF I KNOW YOU HAVE SCAN TOOL. it's not worth posting without an enhanced scan tool.
Just let us know, glad to help.
Note: if passenger side heater is working, its the same module, and this means the module is working. Passenger side requires seat belt is buckled to function.