During the course of moving a refrigerator, you may find that tipping it or even lying it on its back or side is necessary to get it into a vehicle, through a door or up a staircase. While occasionally unavoidable, this process is not ideal and can cause problems to the refrigerator and its motor.
The chief risk to turning a fridge on its side or back is that the fluids inside the appliance's motor may move where they shouldn't go. The oil in the compressor, for example, may move along the oil lines and settle, especially if you leave the refrigerator in a non-upright position for an extended period of time. If oil reaches the discharge line, it can cause damage and a mess when you turn on the fridge.
On most refrigerators, the shelves slide into brackets and remain in place because of gravity. When you tip a fridge, the shelves can slide out of position, which is a hassle if they are made of plastic but can cause damage if they are glass. If you have to tip a fridge, use masking tape to tape the shelves in position or remove them entirely.
Occasionally, you may have to tip a refrigerator for a short period of time during the process of moving in. Doing so won't necessarily cause a problem, but keep the fridge tipped for as short a period as possible. When you set the fridge back upright, wait at least overnight before plugging it back in. This time allows the oil to settle and move back to where it belongs in the compressor.
If you are forced to turn a refrigerator on its side for a lengthy period of time, take a look at the compressor and the owner's manual. The manual should indicate the process tube and the discharge line; the latter often is thicker. Both tubes run from the compressor in opposite directions. When turning the appliance on its side, turn it so the discharge line is above the compression. This position prevents the oil from running into the discharge line.