I have two z-1's one is in my truck and the other is in the wife's van and mine has locked up several times I think due to the heat, because my wife always uses her sun shade and I don't and hers never has locked up until... We went on vacation and I drove her van to the airport and when I parked it I didn't put in the sun shade and two weeks later when we got back it was hot has hell inside and the z-1 froze. So I ran the AC to cool it off inside and we stopped to get a bite to eat on the way home. By the time we left the resturant it was cooler outside and the z-1 was back to normal.