Window air conditioners
Troubleshooting for window and through-wall air conditioners, from the manufacturers' support documentation.
This section is organised by symptom rather than by code, because a window unit's complaint usually arrives as something you can feel, not a number on a display. The page below covers the common one: the unit runs, the fan blows, the air is not cold. It works through the causes in the order GE, Frigidaire, Midea and LG give them in their support documents — mode and set point, the filter, the outdoor coils, an iced indoor coil, Energy Saver cycling, the room's heat load — and stops at the sealed system, which is not a field repair on a room unit.
The most useful step there is a measurement, not an inspection. Frigidaire's guidance is that a working unit drops the air passing through it by roughly 17–20 °F, so comparing intake with discharge separates a failing air conditioner from a room it was never big enough for. A healthy split with a room that never catches up is a sizing question, and the BTU calculator below is where to take it.
Note that Midea's U-shaped window units do show fault codes — EH, EL, EC, PH, PL or PC plus digits — and are not covered here.