There are really good product from HD and Lowes that is good for cleaning this stuff up... it's usually in their aersol aisles...I will normally try the A/T Rust Buster first for removing blower wheels and pulleys. It's a clear, slippery, water like liquid that apparently has been used in auto repair shops since the 1970's, but I only found out about it maybe ten years ago.
I loosen the setscrews and give a few good squirts between the shaft and hub followed by a few light "love taps" to the hub collar with a with a drift punch and ball peen. This usually breaks them loose, but if not, I then completely remove the setscrews and flood the shaft and setscrew holes again and repeat.
If I still get attitude from the blower wheel, I will use a small Uniweld Mapp hand torch that has fairly long reach tip to heat the shaft and hub for about 20-30-seconds, then shock the hub with spray from a bottle of glass cleaner that I always carry patio covers to clean off flux and grubby finger prints. This followed by another quick flood of the rust buster, which gives off a fluffy white cloud when heated, so don’t breath it… and a few more "love taps" will usually do the trick.
Only if all the above fails, is when the hub pullers come out. I have a couple of different sizes of those as well as wheel pullers, but these are rarely necessary.
BTW: "Rust Buster" is the clear liquid from Atwater Supply [A/T], not the brown stuff similarly named "Rust Breaker".
Judging from the odor, I think the brown rust breaker is just repackaged CRC. I've used it and it works, but nowhere near as well as the clear rust buster does on blower wheels or pulleys.