One of the biggest killers of an automatic is heat so a cooler of some kind is a must. Over cooling an automatic does it harm also. A proper auxiliary trans cooler will have a thermostatic bypass installed but this is seldom if ever done by most of us so we end up running the trans at a colder than normal fluid temp for most street driving. Using something the size of an A/C condensor sounds like a huge overcooling.
The 700R4 is prone to convertor failure from overheating when run unlocked over a period of time and a cooler is defintiely a must but a more normal sized aftermarket tranny cooler is all it needs. Keeping the fluid temp abnormally low in an effort to prolong the convertor life doesn't do the rest of the trans much good. If you are running a high stall convertor I would contact B&M or other reputable trans builder and get their recommendations as to exactly how big the cooler should be for your truck and the way it is used.
Mike G
