2004 Freestar Heated Seat Does Not Work

The driver's side seat and backrest do not heat. Passenger side works. All indicator lights work and turn on when I press the heat button. The fuse is not blown. Which wire bundle is the one for the heaters under the seat? How do I troubleshoot this? Where can I find more information / pictures of the wiring bundle under the seat? It's cold in Ohio! Thanks for the help!

In Oct. 2009, I took the seat apart. Found a burned out wire on the seat cushion with some padding melted around it. The wire is a shielded, 2-conductor very thin wire. I spliced it back together and it worked for about a week and now it is inop once again. Very frustrating. Next fix will be to repair it again with some slack in the wire as the first break occurred where there is a metal support rod that attaches to the leather cover.