Questionwhen it is cool outside, my 2005 nissan altima will not go into reverse until it warms up for about 10 - 20 minutes
AnswerHi Bonnie -
Assuming that the fluid level is OK, I would do a couple things:
1. Try replacing the oil, especially if you have not changed it in a while. Make sure the torque converter is drained as well, and the filter screen.
2. There is an additive that I use called AT205. It has saved many people from transmission overhaul, and even has fixed no shift conditions worse than yours. It is sold by Carquest here in Hawaii, I recommend you try it.
If all else fails, you will need a transmission overhaul.
Hope this helps -
aloha
calvin