A window unit looks like an afternoon job until somebody is holding a heavy box over a sill with one arm while the other hand is on the phone. Before anyone picks a day, settle the four things that decide how it goes: who lifts, who braces, who seals, and who checks the drain. Then do the same for the day it comes back out.
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Step one: Read the label and the manual
Find the plate on the side of the unit. It lists the electrical needs, and the manual that came with it says how the unit should tilt, how far the side panels extend, and which support bracket to use. Keep that manual where the next person can find it, not in a drawer nobody opens.
Check the plug against the outlet and the label. If the label calls for a dedicated outlet, or the plug only fits with an adapter, stop and call an electrician instead of improvising with an extension cord or a power strip.
Step two: Set the bracket before the lift
Measure the sash opening and the sill. Most units need a support bracket under the outside edge so the weight does not rest on the window frame alone. Confirm the bracket is fastened to the wall or sill, not just set in place. Then ask the question nobody asks until spring: who owns the bracket, and where does it live between seasons?
Step three: Lift with two people
This is the step that should never be done alone. Before anyone lifts, agree on who calls the count, who takes the weight at the bottom, and where the unit goes once it is in. If your only available helper is a hired person, confirm they are there for the lift itself, not just for the errand.
Step four: Seal and tilt
Fit the side panels and the accordion curtains snug. Tilt the unit slightly toward the outside so condensation runs out rather than into the room. Make sure the drain is clear. Gaps around the panels let in cold air and insects, so the seal is part of the job, not a finishing touch.
Step five: Test and write the owner down
Run the unit on its lowest setting for a short while. Check that cool air comes out the front, that water drains out the back, and that the unit does not rattle in the frame. Then write the routine on a card taped inside a nearby cabinet: who checks the drain, who wipes the filter, and who takes the unit out when the season ends.
The removal is the part people forget
Installing it is the easy half in the sense that everyone is still willing. Taking it out means the same lift, the same two people, and the same bracket. Put the removal on the family calendar under the same name that put the unit in. You are counting two lifts and two sets of trips for every season, and that labor belongs on the sheet with a person beside it. If you cannot find a second pair of hands nearby, the local help page is a reasonable place to start looking.