Not sure whether you're talking about a genuine Volvo auxiliary cooler or just a generic unit.

If it's Volvo, I can explain what I did (see 2 pictures, below). I can't help you if it isn't because I don't know anything about the unit.


First picture: ignore the horns in the center of the picture. At the far laft of the picture is a glimpse of the genuine Volvo auxiliary cooler (for trailer towing), mounted in front of the auxiliary electrical fan (on my '93 240).



Second picture: ignore the electrical connection to the radiator's temperature probe (another story*). What you want to see is the adapter at the bottom edge of the picture, which shows the connector/adapter that redirects fluid returning from the radiator cooler to the auxiliary cooler (instead of just going back to the transmission). Fluid returning from the auxiliary cooler then goes back to the transmission. This sequence (transmission to radiator cooler to auxiliary cooler to transmission) is how Volvo designed this adapter to work. The adapter, and the correct length hoses with their secure threaded ends, are all included in the Volvo kit.



[ * the picture is from an article that I wrote in Rolling, in which I used a Volvo cable designed to turn on the electrical radiator fan if the coolant temperature rises as well as if A/C pressure rises, instead of just the latter.]