Fan making ticking noise at low rpm's. Cleaning / Replacement.

It may be something as simple as needing to clean it, but it could also be that something is broken/damaged with the fan, and so it's making that noise.

Now, looking at the guides that are available for the model I do notice that there isn't one for the fan.

My first suggestion would be to open it up and take a look, (just observe and see if you notice anything like dust or possible broken bits) if there is dust, try and clean it out as best you can, you can use a can of compressed air to do this. Disconnect the battery first.

Now, as I've come to learn, people have different ways of doing things, including cleaning a computer fan. The way that I was taught was to gently press down on the fan to hold it still, and blow the compressed air on it, then let go, turn the fan and repeat until cleaned.

After doing this, reconnect the battery and put the backplate back on (you don't need to screw all the screws back in, just 2 or 3, you can also decide to not put any screws back.) or even leave the backplate off, (Only do this if you know what you are doing and you feel comfortable with it.) and turn your computer on, then listen to the fans, is it still making that noise? If no, then you've probably fixed it and it just needed to be cleaned, if you still hear the noise: There may be bits of dust and debris under the fan or in places that can't be reached without taking the fan out of the computer, or, the fan itself may be damaged.

If the sound continues, this means you may have to take the fan out and inspect it, now this is where I'm unsure, I've done this with other models yes, but not this model, and looking at photos of the inside (fan area), it is a bit complex. I can't find any videos or guides for replacing the fan, so at the moment I suggest just cleaning it out, if the problem persists and you know how to take the fan out and put it back in safely, go ahead, otherwise you may need to see if there's a place nearby that can do it for you.