When I got mine the passenger side switch light stayed on all the time. So, the seat would heat all the time until it decided to not heat. Pretty annoying. I got a new switch from Ford and it seemed to fix it.
The driver side switch would light on and off but the heat would never come. The switch may be bad there too but I don't know. I have a cousin who is the service manager at a Ford garage and he said that it could have a broken heating element in the seat. If so, it would be expensive to fix.
From what I've heard, the switches are prone to go bad on these trucks. Just the nature of the beast. :cry:
Mark