How can i open up the fan of Dell Vostro 3500

wow it seems like you have to disassemble almost every component in order to reach it.. that sucks

first of all thank you for that link, i did not know it.
and its funny how many things you need to remove just to get to the heat sink:

Follow the procedures in Before Working Inside Your Computer.
Remove the battery.
Remove the base cover.
Remove the hard drive.
Remove the optical drive.
Remove the wireless local area network (WLAN) card.
Remove the wireless wide area network (WWAN) card.
Remove the keyboard.
Remove the palm rest.
Remove the display assembly.
Remove the ExpressCard cage.
Remove the system board.
Disconnect the fan cable from the system board.

Best answer selected by nir_jntn.

I had to re-solder some power jacks for some laptops, they all seem to require lots of things to remove like that.