can a window air conditioner unit be installed sideways?

Only if it's been designed that way. You'll ruin a horizontal unit if you turn it sideways.

I think you mean on its end, not sideways - if you put it in sideways, half would be in the room, and half outside, so it would blow hot air into the room as well as cold air, and do the same outside the window.

As far as on its end is concerned, it might sort of work, but the thing is that they output water that has to drip away from the unit and that might not happen put in sideways and that might short out the unit or cause other malfunctions.

They make air conditioners for those windows that slide from side to side, though.

A window air is designed to work with the unit flat not up right. The refigerant inside the unit will pool in the bottom of the coil and will be harder to pump through the system. It puts added stress on the compressor and coil. Therefore, you need to install it the way it was intended to be. You do not want to replace the unit every summer. That could get costly, and if you are going to do that then I would recommend central air.

NO. The compressor would burn out very quickly. The freon is liquid that turns into a gas going through the compressor. Also, the oil would not lubricate as it should.

No. It would messup the freon, or whatever gas is used, inside. The same reason a refrigator needs to be upright for hours before you can turn it on.

Installed, yes. Would it run, for a bit before it is ruined. So it would be a bad idea to turn it on it's edge. Unless you want to ruin it. Then it would a good idea. LOL.

No becuase of the chemicals that help the unit work

No. it is designed to operate right side up.

definately not!!

WHY??