I have a 2010 Sierra Denali with 3200 miles. It has heated and cooled seats that are controlled by an heater/cooler element with a fan blowing air upward in the "cooling" mode. The seats are slow to get up to any noticeable operating temperature. GM Rep and dealer says that's how they are designed - so be it. Any similar problems/experiences out there that can help me out. The option is useless and they got $650 for it.