Principles of Operation (How Does It Work?)

Temperature Controlled Seat System
Both the driver's and passenger's seat has an independent temperature controlled seat system installed. A temperature controlled seat module mounted to the bottom of the seat cushion electronically controls the temperature controlled seat system. The temperature controlled seat system receives power from both the battery power and vehicle run circuits. The vehicle must be running and the temperature controlled seat switch fan speed selector thumb wheel switch in position 1, 2, 3, 4, or 5 for the temperature controlled seat system to activate.

Cabin air is drawn through the set fan motor and distributed to each of the Thermo-electric Device (TED) modules located in the seat cushion and backrest. The TEDs then heat or cool the air. The air is then directed into the foam pad B-surface. Channels in the A-surface of the foam pad are used to distribute the air along the surface of the seat.

Once the system is activated, the temperature controlled seat module uses a set of flexible algorithms to control the heating/cooling modes, and the fan motor speed based on the temperature controlled seat switch settings. These algorithms are designed to protect the user from potentially harmful prolonged exposure to temperature extremes.

The TED uses a "Peltier" circuit of p-type and n-type semiconductors connected in series using copper electrical conductors. The semiconductors are sandwiched between two insulating ceramic plates. When current is applied to the TED, one side releases energy as heat, while the opposite side absorbs energy and gets cold. By reversing the current flow, the hot and cold sides reverse.

Heating Characteristics
^ The temperature controlled seat system draws approximately 10 amps until reaching the set point, and then the system draws approximately 2 amps to maintain the temperature setting.
^ In HEAT mode, the TED can add up to 50-60°C (122-140°F) to the ambient air temperature entering the system.
^ There are two HEAT mode settings based on the position of the temperature controlled seat switch thumb wheel. Position one is the low setting and position five is the high setting
^ In the low setting, the temperature controlled seat module is set to maintain seat surface temperature at 37°C (99°F).
^ In the high setting, the temperature controlled seat module is set to maintain seat surface temperature at 50°C (122°F).
^ If the temperature at one of the TEDs goes above 70°C (158°F), the temperature controlled seat module will the go into an over temperature mode and shut down the TEDs. The fan motor will continue to operate during over temperature mode.
^ In HEAT mode, there is no linear correlation between the thumb wheel position, seat fan motor speed, and TED supply voltage. The temperature controlled seat module will independently vary the fan speed TED supply voltage in order to reach and maintain the temperature determined by the thumb wheel.







Cooling Characteristics
^ The temperature controlled seat system draws approximately seven amps until reaching the set point, and then the system draws approximately two amps to maintain the temperature setting.
^ In COOL mode, the TED can remove up to 8-10°C (46-50°F) from the ambient air temperature entering the system.
^ There are two COOL mode settings based on the position of the temperature controlled seat switch thumb wheel. Positions one is the low setting and position five is the high setting
^ In the low setting, the temperature controlled seat module is set to maintain seat surface temperature at 32°C (90°F).
^ In the high setting, the temperature controlled seat module is set to maintain seat surface temperature at 20°C (68°F).
^ If the temperature at one of the TEDs goes below 18°C (64°F), the temperature controlled seat module will shut down the TEDs. If the temperature continues to drop below 12°C (54°F), the temperature controlled seat module will shut down the fan motor.
^ In COOL mode, there is a linear correlation between the temperature controlled seat switch thumb wheel position, seat fan motor speed, and TED supply voltage. For additional information, refer to the chart.

The temperature controlled seat system is deactivated by one of the following actions:
^ Setting the temperature controlled seat switch to 0.
^ Turning the vehicle off.