Unplug for five or ten minutes and do this. Take off the back cardboard protector and vacuum out the dust on the coils and especially the fan being careful not to bend the fan blades. Hardware stores also sell a bush for the coils. It can reach in places the dirt needs to be broken loose. Once you clean the dirt off it will run cooler. Caution, The fan blades are usually thin aluminum. Just be aware they bend easy and can be bent back into shape.