Hi Rufer,
Welcome to the Heartland Owners Forum and Family. We have a great bunch of people here with lots of information and all willing to share their knowledge when needed.
No,, it's not normal for the breaker to trip before all the slides are in.. but I have heard some say that in the really sub freezing temps that are around now that the fluid could get really thick and heavy. So it is possible for that to happen if your way up North I would think. You don't say where you are, but if your in CAN in the really cold,,, I can see it happening.
You might give us a little more information as to your location and model and year of your Cyclone. I'm sure some of our other members will jump in soon.
Enjoy the forum and your Cyclone.
Jim M