Heated seats were an option on the 94 Seville/STS. The controls are located in the center councel, directly in front of the storage compartment hidden below the armrest. They are in a 2.5 x 3.5 inch black box with grey stripes on it. A common problem for those cars was for the heated seat control knob to break off leaving you with a flat indent where it should be. They can still be used if the knob is gone, you'll just need a pen or something to move the switch.