The driver and front passenger heated cooled seat system consist of the following components:

The heated cooled seat system operation is controlled through the switch inputs of the HVAC control module. The heated cooled seat switches provide 3 inputs that are relayed to the Memory Seat Module (MSM) through GMLAN messages. Whenever one of the switches is pressed a message is sent to the MSM indicating switch is active. During heated cooled seat operation the HVAC control module displays the switch symbol of the active operating mode and the temperature level bars on the climate control display. The mode symbol and temperature bars that are displayed is determined by a GMLAN message from the MSM.

The memory seat module monitors the heated cooled seat switches through GMLAN message inputs and determines the heated cooled seat operating modes and temperature levels. When heated or cooled seat switch active signals are received through GMLAN messages, and vehicle conditions are appropriate to allow heated or cooled seat operation, the memory seat module (MSM) will calculate the switch activations and determine the heated or cooled seat operating modes. When the MSM activates a heated cooled seat function an indicator control GMLAN message is sent to the HVAC control module. The MSM controls the operating mode of the Climate Control Seat Module (CCSM) through 2 pulse width modulation (PWM) signal circuits. The left and right heated/cooled seat mode signal circuits are referenced from battery voltage by the CCSM and pulsed low by the MSM. Each heated cooled seat is capable of operating in 3 modes with 3 temperature levels so the MSM uses 9 PWM frequencies for each signal circuit to command the heated cooled seat modes to the CCSM.

The Climate Control Seat Module (CCSM) is located under the passenger seat and controls 4 individual driver and passenger seat heat/cool ventilation blowers. When the CCSM receives a heated cooled seat command through the left or right heated/cooled seat mode signal circuit, the appropriate seat heat/cool ventilation blowers will be operated by the CCSM.

The ventilation blowers are self contained electronic air conditioners consisting of a blower motor with an inlet air filter, thermal electric device (TED), temperature sensor, and waste air duct. The air flow from the blower is divided into 2 streams and directed across both sides of the TED, one side into vent passages through the seat foam and the other out the waste air duct. While the system is operating in either the heat or cool modes both heated and cooled air is generated as it passes across the TED. When voltage is applied to a TED, one side releases energy as heat, while the opposite side absorbs energy and gets cold. Heat or cool modes are determined by the polarity of the supply voltage to the TEDs. The climate control seat modules (CCSM)s rely on inputs from temperature sensors located in the ventilation blowers near the TEDs to control seat temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the CCSM. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the TED temperatures rise. The CCSM monitors the temperature of the air flow into the seat foam and continuously adjusts the blower speed and TED temperature by regulating the current flow through each component.