check the fuse first. The switches can get full of crud (they are in a bad place). You can take them apart and clean them. There is also a very good chance the heater wire is broken in the seat at the thermostat. If you have a multimeter its easy to test for these problems. Unplug the heater wire under the seat. With the ignition on, and the heater switch on you should get 12 volts on the car side of the plug. If you don't get 12 volts its either the fuse or the switches. Check for resistance(continuity) on the heater side of the plug. If you get low resistance the heater is OK. High resistance indicates the heater is broken. Note that the seat must also be below 62 degrees for this test otherwise the thermostat will be open. If the heater is broken you can solder it back together, but you have to take apart the seat to do this.