Pressure washing can force dirt into bearings and other places you might not want it. Stick with a garden hose with a good, strong sprayer
From participating in clean up discussions for a few years on here, here's what the consensus seems to be:
- Blow off dust and loose dirt with an air compressor
- Remove electronics tray and air filter
- Cover remaining air filter assembly with a tightly sealed bag (using a zip tie).
- Using a garden hose sprayer, hose off dirt BEFORE applying cleaner
- Spray liberally with your favorite degreaser (Simply Green, Muck Off, etc.)
- Work degreaser into all surfaces with a small brush (I use an old toothbrush)
- Let cleaner do its work for 15 minutes or so
- Using a garden hose sprayer, hose off the car/truck
- Blow off standing water with an air compressor
- Gently clean electronics with spray cleaner
I'm air compressor challenged for now so I use my leaf blower instead.
Many on here have found that the foam element air filters clean up quickly with Dawn dish detergent. Rinse it thoroughly and wring it dry. Allow it to finish air drying before putting it back on.