I didn’t say cleaning would solve it. I said that a service tech should look at it and it was possibly a simple fix.
Also window units will have to fight against the rest of the house being warm. Interior walls are seldom insulated, warm air drafts in around the unit and around doors. A window unit in one room could cost as much as a dedicated unit for the whole house, as it has to work harder to maintain the desired cooling.
Same as everywhere else