How to Install the Sill Support on an LG Air Conditioner

Measure the area in front of the windowsill. Cut a piece of 1-by-2 inch wood the length of the sill. Place the wood piece horizontally inside of the home with its full length and the shorter edge butted up against the windowsill. Hammer two nails, one on each side, into the wood to secure the wood to the inner side of the window. The wood should be slightly higher than the window sill by about 3/4 inch.

Cut a 6-inch-long piece of 1-by-2 inch wood. Place the piece of the wood horizontally just outside of the window on the ledge. Butt the shorter side of the wood piece up against the outside windowsill, so that there are now two pieces of wood laying down against both sides of the windowsill. Hammer two nails, one on each side, into the top of the wood piece, until it is secured to the house.

Place the two supplied L brackets onto the outer wood piece. Face the longer, flat piece with the hole flush against the wood and butted up to the outer sill. The shorter side of the L bracket should be adjacent to the wood and facing away from the window.

Place two of the supplied screws into the holes of the brackets, one for each bracket. Screw the screws into the wood with the screwdriver, until each bracket is secure.

Place the bottom guard of the air conditioner against the bottom of the air conditioner, if it's not attached already, and line up the screw holes of the unit with the guard. Place supplied screws into the guard holes and screw them in with a screwdriver.

Insert the air conditioner into the window. Settle the bottom guard of the air conditioner into the space between the windowsill and the back plate of the two L brackets on the outer wood.

Place the supplied type-H brackets on either side of the inside portion of the unit, so that the bracket is against the air conditioner and the inside wood. Screw the supplied screws into the brackets, fastening the unit to the front portion of the wood.