The goal of this project was to build a model and a controller for the seat heater and steering wheel heater on the SAAB cars. SAAB manufactures two different car models 9-3 and 9-5. The goal is to control the seat heater in both car models without any temperature sensor in the seat, this due to cost reduction. Several tests have been carried out booth in climate chambers and during road tests. These tests have in the end lead to a mathematical model for the temperature dependence and this model has been used to design an open loop controller for the seat heater.