As far as I know, the cooled seats were only available on the 2004-2006 Platinum Escalade ESV, and they do have a cooling element to them. Here's how they work:
Each heated/cooled seat is controlled by a climate control seat module (CCSM) located under the seat cushion. The CCSM is supplied with battery voltage, ignition voltage, ground, and a mode signal circuit. All heat/cool seat modes will operate with the ignition on without the engine running, although due to the high current draw inconsistent operation could occur. When verifying a customer concern doing so with a fully charged battery and the engine running will provide the most consistent results. The CCSM controls heat/cool seat ventilation blowers located under the seat cushion and behind the seat back. 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. The supply voltage to the TEDs is controlled by the CCSM and the polarity determines which side gets hot or cool. When the polarity of the current flow to the TEDs is switched, the hot and cool sides of the TED reverse. 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. The CCSMs 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.
That said, it does actually work like it says in will during the summer. 
