Can a window A/C unit be installed on its side?
Absolutely not on its side!!! I know of NO compressors that can be installed on there side the lubrication will not stay in the compressor and it will fail in a very short time! This is not a uninformed opinion I have EPA 608 universal license (3) and a 609 license. Laying a unit on its side during shipping is enough to destroy a unit if not left in the correct position for a few hours to 24 hours to allow the oil to return to the compressor.