My Central air conditioner is making a louder humming noise then usual and is not blowing cold air It was working in the morning then stopped blowing cold and got noisey in the afternoon help and ty?

check and see if evaporator coil restricted, coil frozen, if not check pressures sounds like unit running but not shutting down, if coil frozen oil may be carried from compressor and leaving compressor with no lubrication repair before burning out compressor.