If the bathroom door swings open by itself, then my drivers side is low. I usually find this out after I disconnect the trailer but it gives me an idea of how accurate the outside level is for side to side.
For front to back, if the A/C is dripping from the front, then the front is too low. At least I can correct this after disconnecting. Again, this can be a way to check the accuracy of the outside level.
If the fridge is off enough to affect operation at this point, I’ve got big problems.
