Heated Seat Operation

WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

When the heated seat switch is pressed for High Heat, the climate control seat module (CCSM) will transition to the HEAT state. In the heat state, the CCSM applies a pre-determined voltage through the ventilation module heat control circuits to the heat side of the thermo-electric devices (TEDs), while providing a ground through the ventilation module cool control circuit to the cool side of the TEDs. A pre-determined voltage is also applied to the blower motors. The CCSM uses the following sequence beginning with the Heat SoftStart Mode to achieve the set point temperature before it can enter the Control Heat Mode. If the seat temperature is already above the Temperature Set Point, the CCSM will skip the Heat SoftStart Mode and proceed to the Control Heat Mode.

Heat SoftStart Mode-While in transition to the heat mode, the CCSM will initiate the SoftStart Mode. The intent of the Heat SoftStart Mode is for the module to bring the ventilation module fin temperature up to the pre-determined Temperature Set Point of the Max Heat Mode. The module does this by setting the blower motor speed control to a pre-determined voltage while ramping up the ventilation module voltage from 0 volts to the maximum voltage, not to exceed 5 seconds, at which point the system transitions to Max Heat Mode. The Heat SoftStart Mode will only be attempted once per ignition cycle.
Max Heat Mode-Upon completion of the Heat SoftStart Mode, the CCSM will initiate Max Heat Mode. The intent of the MAX Heat Mode is to maintain the fin temperature to the pre-determined Temperature Set Point in order for the CCSM to go into the Control Heat Mode. The CCSM does this by maintaining the TED at the maximum voltage while maintaining the minimum required airflow across the fins. After max heat duration has been reached, or upon achieving the pre-determined Temperature Set Point, the system transitions to the Control Heat Mode.
Control Heat Mode-At the completion of Max Heat Mode, the CCSM will initiate Control Heat Mode. The intent of the Control Heat Mode is to maintain the desired fin temperature or the set point temperature. The CCSM does this in two ways; first by adjusting the voltage supply to the blower motor to control blower motor speed, then secondly by controlling the voltage supplied to the TED. The CCSM updates these voltages once every second. Increasing the blower motor speed will decrease the fin temperature. If the maximum blower motor speed is achieved and the fin temperature is still above the set point of high heat, the CCSM will then begin to control the TED voltage to achieve Temperature Set Point. Decreasing the TED voltage decreases the fin temperature. If the CCSM is trying to raise the fin temperature to set point by using TED voltage, and the fin temperature cannot be raised because the TED voltage is at the maximum, the CCSM reduces the blower motor speed to achieve the Temperature Set Point.