Hi Mark, Having just went through this recently, I purchased off Amazon, Supercool 22779 A/C Flash Flush as it claims to not leave any residue. I went to Autozone and rented their solvent flush gun, hooked it up to my compressor and was pleased with results. I thought it did a great job of cleaning. I did my evaporator and condenser 3 times and the hoses a couple of times. There is a good YouTube video, "How to flush Auto A/C systems" by Centurybob that took the guess work out of how to perform this task. Plus it helps that he's working on a Olds Cutlass. Best of luck! Dave
