I find that if I have to have the kb in a hot car for a period of time, I'll try and go out every few hours and run the a/c on high for about 5 minutes. Usually these instruments are in decently insulated cases, which keeps a lot of the heat out. If you run your a/c every couple hours, it makes the maximum temperature inside the car much lower than if you just let it bake in their for 8 hours or so...