I've seen this question here a lot... And I'm not sure of the answer. You obviously won't have the same problems (as with an absorption fridge) if off level, and it probably doesn't matter for a little while. But - our home A/C had gone off level by a bit over time and when we looked it up to see if it mattered we found this:
"Another reason that the condensing unit must be level has to do with the oil that mixes with the refrigerant. There’s always some oil that escape the compressor and travels with the refrigerant through the lines.
As long as the unit is level, this oil comes back to the compressor and gets redeposited where it’s needed. However, if the unit isn’t level, then the oil may separate from the refrigerant and end up pooling in the lines and coils.
Over time, this can lead to a shortage of oil in the compressor, causing damage and overheating. Additionally, oil coating the inside of the coils can make it harder for heat to transfer, decreasing the system’s efficiency."
Link to site.
