... in cooling mode, direct entry of sunlight
into the room: draw the curtains.
...  installing  in  places  near  heat  sources,
which could damage the unit.
... loose electrical connections.
... loosening the coolant connections after
connecting  them  (loss  of  refrigerant
charge).
...  too  many  bends  between  indoor  and
outdoor  units  (see  outdoor  unit  installation
manual). 
Excessive  distance  between  indoor  and
outdoor  units  (see  outdoor  unit  installation
manual).
...  routing  the  condensate  drain  pipe  to  a
residential drain or sewer network without a
siphon. The height of the siphon in relation
to  the  available  head  must  be  such  as  to
allow correct evacuation of condensate.
...  crushing  the  coolant  connection  pipes
and the condensate drain pipe.
...  an  excessive  height  difference  between
the  indoor  and  outdoor  units  (see  outdoor
unit installation manual)
GB-4