Best way to flush transmission cooler lines?

I am in the process of installing a Jasper reman transmission in my 2006 GMC Sierra. I just finished getting the factory 4l60e transmission out. Needing to flush my factory cooler. Pretty sure the process should be the same for any vehicle with Auto Trans.

Those of you who have experience in flushing cooler lines what is the best way to do this? 1. Use compressed air to blow the lines out? 2. Blow from both directions? 3. Should I use a solvent of some sort such as brakleen and blow that through?

Bird said:

I've just used a small air compressor and nozzle like the one pictured but done so for only peice of mind.

I tow a lot and have messed with many auxiliary coolers on my GM trucks and have yet to find a clogged line.

By the way,I've been through (4) 4L60e transmissions.

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I tow some with mine also, pull a 24' baja in the summer. Had it rebuilt a few years ago. Got hot again last summer and would no longer shift into 2nd gear. Both times heat were the culprit. Installing a tranny temp gauge into my dash so I actually know if it's getting too hot. They make transmission cleaner in an aerosaul can, wasn't sure if that was for someone who doesn't have an air compressor or if it contained a solvent to help flush the cooler?