Doug:

don't pay some jack-leg $72!!!!!!

go to your local Johnstone Supply (in the white pages)

ask for a gallon of purple Alki-Foam (the #1 selling foaming lye-based coil
cleaner in the world) about $8 or so

put in plastic squirt bottle (1:1 ratio, i.e. 1/2 water, 1/2 purple stuff)
always add purple stuff to water, not vice-versa

set breaker near unit to OFF position

while wearing gloves & goggles for safety, spray liberally into coil all
over, take it slow & thorough
this is bad stuff, don't get in skin or eyes (it is essentially oven
cleaner)

wait 5 minutes, it will foam up during this time

spray off thoroughly with garden hose with sprayer attachment

turn breaker back on

enjoy lower utility bill!

S.F.