Sounds like either a vacuum line issue to the CAD or the CAD itself. There is a vac line "plug" (so to speak) on top of the t-case you can easily see from the drivers side. Follow them all and look for cracks or leaks. Behind the front passenger tire on the axle, you'll see two vac lines that plug into the Central Axle Disconnect. I'm currently having the same problem with mine, need to get into it, like you, when the weather gets a few degrees warmer... There are several posts and threads on here regarding this issue. If the CAD is the issue, probably very simple fix. Like gunked up with crap and can be cleaned and soaked with PB Blaster, so I've read. Good luck!!