For my 2012 Maxima, the service manual has a "CVT Fluid Cooler Cleaning Procedure" (page TM-151 of the FSM). The procedure consists of 17 steps, including spraying cleaning fluid into the cooler lines, and also blowing compressed air through them, and then repeating the process three times. Which sounds like it would get the cooler really clean.

But the last step of the cleaning procedure is to perform the "CVT Fluid Cooler Diagnosis Procedure" ( page TM-152). In this procedure, you also disconnect the cooler lines and blow compressed air through them. What's different is that this time, you put a coffee filter over the cooler line where the compressed air is coming out; that way you can catch any debris that might be blown out of the cooler, and inspect it (depending on the size of the particles, you may have to replace the cooler).

But here's where I'm confused: How could there still be debris in the cooler when you've just given it a thorough, multistep cleaning, and repeated it three times? Shouldn't you do the diagnosis (debris inspection) *before* the cleaning?

I figured it was just a mistake, and they meant to put it in the opposite order. But the order is the same in every manual I can find that includes both procedures. So now I'm thinking that I'm missing something (which often happens), and that there's a perfectly reasonable explanation for doing it in this order. Assuming that's true, does anyone know what the reason might be?