Seems when the weather is hot(85+) and the humidity is up(50+) I can't engage or disengage my over drive. I keep pressing the button but nothing. Then later at night or in the morning when it's cooler it works fine. Anybody have or heard of this? My JK will be 3 years old next month with about 36000 on it.

 

Probably a switch issue.

If mine was doing that, I would pull the switch out, and jumper the terminals, or the sockets in the vehicle side of the connector.
That would tell you if it's the switch or not.