Seat warmer not working in driver’s seat.
A blown fuse is a possibility but fuses don’t blow for no reason. If the fuse is blown the circuit is drawing too much current. It’s also possible there’s a loose connection somewhere. The seat is subject to a lot of flexing and over time the wires can get disconnected.
Check the fuse, switch, and heater itself in that order.
And, don’t forget to check the integrity of the electrical line that runs into the seat.