Laptop making a high pitch whirring sound?

[Nolan]

My dell laptop is relatively old. Only had it for about a year and a half. It's always been just a super quiet machine, unless I really pushed it to it's limit, when you could hear the fan blowing. Now, I was just using it and it seemed to be getting hot, this happens very rarely but I had left it on my mattress for a while so the heat really built up. I noticed the heat from the vent on the side and like an idiot, I blew into it in an attempt to cool it. Then a tiny puff of dust came out from the vent, and seconds later, it began to make a high pitch whirring sound I've never heard it make before.
Is something wrong with the fan? What do I do to fix it? Or where should I take it to be fixed?
The sound is pretty much continuous. At times it gets quietter, louder, and even stops at some times but only for a short while.

[Dell Inc.]

Hello Nolan,

I am from Dell Social Media and Community.

Over a period of time there is dust collected in the air vents and fan, follow the link below to troubleshoot this noise issue.
http://support.dell.com/support/topics/g...cid=428053

If this has not helped you or if you need any further assistance, feel free to message me on Twitter(@NiranjanatDell). I will be happy to assist.

Dell-Niranjan