Going to Johnstone on monday, and get some coil cleaner. This stuff looks good. Dilutes 1-4 for condensors, 1-8 for evaporators.
Enviro-Coil Coil Cleaner B81-474
The alki foam stuff I'm using dilutes 1-1. So the more expensive stuff dilutes down farther, and is cheaper in the long run.
What do you guys use? I've got a job next week, cleaning some BIG outdoor condensing unit fins. I started the job with alki foam, but the part of a jug I had didn't go very far, and I'm needing another jug of cleaner.