no compressed air is fine,when you clean the fans make sure you hold them still so they dont spin realy fast when you spray them because i heard it can damage them.
i also use cotton tips to clean my fans because simetimes air alone doesnt get all the gunk stuff off the blades.
and a bit obvius but make sure you keep the can of air upright or it drips.
If your smart you'll use a leaf blower , nah im kidding but a shop vac that blows works really well. That or an aircompressor works well. Just make sure to hold it a tad farther back. It will save you money on the crappy cans that dont put out enough air. Every 6 months blow it out and your good.