I also have a 2000 v-6 SE with ATX. I have the same problem but mine won't shift into 1st after 25 MPH regardless of wheather or not I'm using the A/C or defroster or even manually shifting into 1st. I believe it is to protect the trans as well since it is computer controlled. Kind of sux when you need just a bit more power then 2nd will give if you ask me. Just my two cents.
