DIAGNOSIS If the fan runs but the air is room temperature, the cooling cycle isn't engaging. The most likely culprit is an installation issue: the exhaust hose isn't connected properly or the window kit isn't sealed, causing the unit to overheat and shut the compressor off to protect itself.
FIX Go back to your installation. 1) Verify the exhaust hose is clicked and locked onto the back of the unit and the window adapter. 2) Check the window seal. The adjustable panel must fill the entire window opening—use the included foam seals to block any gaps where hot air can get back in. 3) Close the drain plug if you opened it for storage. Once the sealing is confirmed, turn the unit off via the remote or button, wait 5 minutes, then turn it back on Cool mode at a low temperature (like 68°F). You should hear the compressor click on within a minute.
IF THAT DIDN'T WORK Listen closely when you first power on Cool mode. Do you hear a single loud click followed by a low hum? That's the compressor. If you hear no click, or a rapid clicking, there could be a power/control board issue. Try plugging the unit directly into a wall outlet, not a power strip or extension cord, to ensure it's getting full voltage.
HEADS UP These units need a few minutes after starting to begin blowing noticeably cooler air. Don't judge it in the first 3 minutes. Also, on very humid days, the air might feel less cold because the unit is working hard to remove moisture first.