You can clean the AC fins using compressed air if:
1) You use reverse air flow - shooting compressed air
in from the clean side. If you can't get access to
reverse flush, then you can experiement with hitting
the fins at a very oblique angle - you are hitting
the fins sideways. This isn't as effective, but better
2) You don't smash the fins with high psi air.
I use a special kind of blow gun with produces
a very high volume of air with a much reduced
psi. Available at Harbor Freight and other outlets
for compressor items. The barrel of the air gun
has openings at the base to entrain ambient air
(suck in outside air) as the compressed air moves
through the barrel. This entrained air greatly increases
the volume of air and also slows down the airflow.
3) You lightly loosen the debris carefully with an old
soft toothbrush or some other very soft brush.
Obviously, you should brush with the fin direction
and not against it.
I'd suggest picking up an inexpensive fin straightening
tool (also available at Harbor Freight). Have it handy to
touch up any areas where you accidentally smash the
fins. You can also straighten them with an old knife,
but thats pretty slow.