For the curious, here's a description of how they work.
http://deneau.info/ls/s6x~us~en~file=s6x1a003.htm~gen~ref.htm#extract_40
Climate Controlled Seat System
Both the driver and front passenger seat has an independent climate controlled seat system installed. A climate controlled seat module mounted to the bottom of the seat cushion electronically controls the climate controlled seat system (CCSM). The climate controlled seat system receives power from both the battery power and vehicle run circuits. The vehicle must have ignition ON and the dual automatic temperature control unit (DATC) module switch set to HEAT or COOL 1, 2, 3 or AUTO for the climate controlled seat system to activate.
AUTO mode is achieved by pressing the HEAT and COOL settings simultaneously. The center LED will be illuminated when the CCSM is in AUTO mode.
Cabin air is drawn through the seat 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 climate controlled seat module uses a set of flexible algorithms to control the heating/cooling modes, and the fan motor speed based on the climate controlled seat switch settings. These algorithms are designed to protect the user from potentially harmful prolonged exposure to climate 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 2 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.
The temperature differences between the individual HEAT and COOL settings is minimal. For example, it is difficult to distinguish between LOW COOL and MEDIUM COOL settings. Monitoring the seat temperature at different HEAT or COOL settings should not be done as it is ineffective in confirming climate controlled seat system operation.
Heating Characteristics
NOTE: The presence of overtemp faults (DTCs B2729 and B2730) can be induced by incorrect operation of the climate controlled seat system after an initial HEAT setting has been attained. If a HEAT setting is repeatedly turned OFF and ON in an attempt to increase the seat temperature, an overtemp condition can result and the DTC(s) will be set.
* The climate controlled seat system draws approximately 7.5 amps until reaching the set point, and then the system draws approximately 2 amps to maintain the climate setting.
* In HEAT mode, the TED can add up to 40-60°C (72-108°F) to the ambient air temperature entering the system.
* There are 3 manual settings based on the position of the climate controlled seat switch on the DATC module. Position 1 is the LOW setting and position 3 is the HIGH setting.
* There are 5 AUTO HEAT settings. The AUTO HEAT setting is determined by the temperature setting of the DATC module when the CCSM is in AUTO HEAT mode.
* In the LOW setting, the climate controlled seat module is set to maintain TED temperature at 37°C (99°F).
* In the HIGH setting, the climate controlled seat module is set to maintain TED temperature at 65°C (149°F).
* If the temperature at 1 of the TEDs rises above 85°C (185°F) in the HEAT mode or 70°C (149°F) in the COOL mode for more than 4 seconds, the CCSM will record an overtemp DTC, remove power from the TEDs and go into BLOWER ONLY mode in an attempt to cool down the TEDs. If the TEDs temperature has not dropped to 80°C (176°F) in the HEAT mode or 65°C (140°F) in the COOL mode after 30 seconds, the CCSM will shut down and remain off until the ignition is cycled. Also if the CCSM detects an overtemp twice during the same ignition cycle, it will also shut down.
* In HEAT mode, there is no linear correlation between the (DATC) module, the seat fan motor speed and the TED supply voltage. The CCSM will independently vary the fan speed and the TED supply voltage in order to reach and maintain the temperature determined by the (DATC) module setting.
* Cooling Characteristics The climate controlled seat system draws approximately 7 amps until reaching the set point, and then the system draws approximately 2 amps to maintain the temperature setting.
* In the COOL mode, the TED can remove up to 8-10°C (14-18°F) from the ambient air temperature entering the system.
* There are 3 manual settings based on the position of the climate controlled seat switch on the DATC module. Position 1 is the LOW setting and position 3 is the HIGH setting.
* If the temperature at 1 of the TEDs falls below 18°C (64°F), the climate controlled seat module will shut down the TEDs. If the temperature continues to drop below 12°C (54°F), the climate controlled seat module will shut down the fan motor.
* In COOL mode, there is a correlation between the DATC module, the seat fan motor speed and the TED supply voltage. Fan supply voltage is used in the following equation (seat fan motor supply voltage/0.74 x ignition voltage) to determine the fan duty cycle. For additional information, refer to the following chart.
