Check the following:

Is the air filter dirty?

Is the air conditioner's intake grille or outlet port blocked?

Did you set the room temperature (thermostat) correctly?

Is the window or door left open?

While the air conditioner is in cooling operation, does the window allow bright sunlight to enter the room?

While the air conditioner is in cooling operation, does the room have any heating equipment or computer in operation? Are there many people in the room?

Is the unit set to Super quiet mode?

---