My air conditioner is running, but it’s not very cold. What’s wrong?

The chances are your unit is low on refrigerant; somewhere there is a leak. The leak should be fixed before re-charging with refrigerant (by someone certified to handle refrigerants), otherwise it will leak out again.  You can visually check the coils of the outside unit to make sure it is not excessively dirty or blocked. If the coil is dirty, you can flush it with a garden hose, keeping water clear of electricals.  Check (listen) to see that the compressor is running; if not, you will require an a/c technician. You can also check to make sure that any air return duct in a hot area is not broken, split, or disconnected.