Inspiron 15 7577, weird fan noise

Hello i have a inspiron 15 7577 and its making a weird fan noise like the left fan is hitting the side of the laptop. It happens all the time not even when its in load even doing something as simple as browsing the web or watching a youtube video when its under load like gaming the sound stops appears every couple minutes not sure i need to replace the fan or where i can buy a replacement fan or where would i send it to be fixed.