Hose adapter
It helps alot if you can find one of the hose adapters that have a long wand and a spray tip. Bend the tip to as close to a right angle as you can. If you can keep the bent end or tip to less than an inch or so, then you can use the wand to get beween the condenser and the radiator and spray at right angles to the radiator. This is the most effective way to clean out the fins without bending the fins from the water spray.
I made a wand out of a length of 1/4" copper tube and crimped the end to make a spray pattern.
Any good degreaser or Simple Green or other strong detergent will work, just rinse thoroughly.
Hope this helps Greg L. The Noise Nazi