I have a CR-10S Pro V2 and like you, just threw a spool of polymaker ASA on it, tweaked the stock profile with turning off the fan, setting retraction to 4mm, first layer nozzle/bed temp at 265 then 150, 105 then 90 and lowering the Z height on the printer by like 0.04mm for a good first layer adhesion/squish.
Before playing with anything but the retraction, my benchy would warp and detach at 0.2", right at the deck height. After turning off the fan, like you, i got an almost perfect benchy.
Feeling emboldened i jumped right into attempting a 12hr print of a car grill emblem, 0.16mm layer height that measured 3.5"x 9.5" x .675" and it would warp at about 2/3’s of the way through, even with a brim. The quality looked amazing up until the detach/warp. It happened at the same spot each time, a interior corner. I tried glue stick…nope, Aquanet hairspray was better, but the print still detached/warped each time in the same spot. It failed 4 times in all.
Last night I tried again, same print settings but with the addition of two things: a Comgrow tent enclosure (inside temp stabilized at ~40c) and a PEI steel plate bed from Creality.
This time it came out perfect, no warping! Gonna try the other half now.
If you get it dialed in, you should definitely reprint your fan shroud in ASA.
edit: I just double checked my PETG fan shroud and found that it melted, lol.
I’m on my second spool of ASA and love it. It did require me to upgrade to a enclosure and PEI print bed.