No there is no "button". As the heat is absorbed, the cockpit is cooled. Same as any cooling devise. Like your home AC, cool air comes out one side, and hot air comes out the other side. Freezers and refrigerators work on the same principle, but in a nascar car it's taken to an extreme. There is no fan to blow the hot air out, like in your home ac. It absorbs heat into a monotwin vapor receptacle, otherwise known as a steam bucket. The heat builds up until it reaches combustion. When it conbusts, a 3-phase direct current motor pumps the heat out the side of the car through the fender sprocket.
When the super heated steam hits the oxygen in the air it ignites and that is the flames that you see. That's why you see the flames more at night races than during the day. As the air cools at night, more oxygen settles near the ground or in this case the track.
This is as non technical I can make it. Maybe somebody can add to what I said or explain it better than I did.