I'm going to flush out my heater core on my 2000 Maxima, and would like to know what code to set my auto climate control system at in order to lock it in the hot position when my car is off. If you hold down the off button on the system for 5 seconds you can dial between 4 codes: 2, 3, 41, and 51. I know that one of them locks the system open, but which one?