Im hooking up a trans cooler on my 2004 Blazer, on the original cooler lines that go into the radiator, theres a top and bottom. Which one is the in, and which is the out? Thanks!

 

https://blazerforum.com/forum/2nd-ge...g-80010/page2/

 

The upper connection is from the trans, (hot). The lower connection goes back to the trans, (cooled).

I installed one of these coolers on my 98, (220K miles) and one on my 04 Blazer, (110K miles). Mounted to the radiator core support in front of the A/C condenser. Totally bypassed, (eliminated) the factory cooler in the radiator. Trans temp on both vehicles consistently runs ~60F above ambient temperature, Winter and Summer, with and without towing. Both vehicles have the original transmissions, never been apart, just regular fluid & filter changes.

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