will you be placing the outdoor unit on your terrace/balcony? or hanging outside your window?

as both are temporary and require no fixed installation, it should be ok.

Thanks for the reply Epicure.

How heavy is the secondary (outside) box? on average. 

Would it be able to hang outside a window without having to install steel screws?

usually they have a "U" shaped brackets which hang on to the window ledge.

Suggest you read your rental contract to make sure there are no specific clause which would forbid outside installation on the building facade or request  a written demand for authorization to allow for an exception.

I agree with Milord.  There are rules about outside installations, so going ahead without authorization could cost you dearly.

If you are putting in a split machine, you may need a professional to install it as the lifeline has to be dismantled to get it through a hole in the wall.  There is no use running the life-line through a partially opened window - save your money, time and effort - the outside hot air will just creep back in.

As to hanging the satelite unit out the window, not a good idea either as it will have to be bolted on so as not to fall and kill someone on the sidewalk.

Alternatively, you could go for the units that deject the hot air outside  . . . just get some wood, stiff cardboard or plexiglass, cut a hole for the vent, open the window and fit the board into the window space so as to have a sealed replacement.  Presto.

i have an a/c unit. it expells the hot air via a plastic hose about 10cm in diameter. by placing this through a slightly open window and foam to fill in the open areas, it works very well. it is only temporary and the hose is held in position by the window blinds on the outside. it works fine foe an average sized bedroom.

Thanks for the help everyone.

I ended up buying a regular AC unit with the hose/exchause due to the uncertainty of the former. Of course Murphy's Law strikes and now the temperatures have dropped significantly. 

But such is life...

Thanks for the help though.

Likes for all.

Those temperatures will surely come again so you should get your money’s worth in due course.