Got 2 questions:
1) What direction does the oil flow through transmission? Does it flow from line through external cooler filter, into the tranny or is it the other way around (from tranny, into cooler filter, into line)?

2) Can I pneumatically flush the old fluid and have good results? If so, where do I input air pressure? Should I apply it into the line that attaches to cooler or should I apply it where the external cooler filter screws into tranny housing?

Here is my thinking: My wifes 2001 Acura CL Automatic Transmission was replaced under warranty at 50K and what is in it now is a BGFA tranny. Bought this car used and was not aware of this until a few days ago when I called dealer and provided VIN. Anyway, not sure when oil was last changed but after having light come on a few days ago (Code P0740), I decided to do a fluid flush and replace external cooler filter as well.

Pulled the external filter off, the fluid is dark and I'm concerned of possible overheating issue. I am wondering that if there is a build up of material on the INTERNAL filter, then perhaps by applying some air pressure (probably a low pressure) through the lines, opposite of fluid flow, it may cause some of the material (if any) that has accumulated on the filter to dislodge and fall into fluid, which will flow out when I drain it.

Just trying to think of ANYTHING I can that may help my efforts to get this light to go off, which I would assume is from low fluid flow, yet I don't want to do something that may cause further problems.

Any thoughts or suggestions?

 

Got same OBD error codes on mt cls 02 - this is one of the most common issues -an indication that tranny is going to fail soon. I tried to drain the tranny fluid 3x3 (3 quarts - 3 times ) - same issue - Eventually it had some closed calls on the freeways - where the gear just downshifts by itself and issues on shifting gear from 2-3 - I occasionally hear a "thud" sound and jerks the car whenever it tries to shift.
About your questions
1. for sure on that hockey puck tranny cooler has 2 lines external hose - 1/2 that goes to the engine -- and the 5/8 (i forgot where it goes ) and dont know the direction of the fluid lines. There are some members here that are very knowledgeable with this and hopefully answer your question.

2. It might help if you put air (not recommended) - but it will not drain all of the fluid - thats why we do 3x3 fluid changes

I think you might be leaning towards on replacing with a rebuilt or used tranny. What i did is replaced it with 06 Odyssey transmission - same exact thing with minor changes - instead of using that weird hockey puck transmission - it uses an external radiator type transmission cooler (3/8 size hose). I already put almost 20k now on that odyssey tranny and works like a charm. There is a forum here that discusses on tranny swap. go check it out.