You could try renting a compressor. Get 25' worth of hose, a directional blower nozzle, and EAR PLUGS.
You might try wrapping the immediate area into a contained perimeter (like a 40 gal plastic bag) and then blow the **** out of it.
You should be able to vacuum it after that.
The problem is, the radiator is probably a little grimy as well, so just blowing it off won't solve the long term problem. You will probably have to break down and do the windex and toothbrush thing, or something, to really get them clean in a way that they won't stink when they're on, and don't collect dust so quickly in the future.