I watched a video recently where Lemon Tea Leaf tested whether cabin temperature affected battery temperature.
Lemon Tea Leaf's test results where inconclusive but I think there may be value in employing this battery temperature controlling strategy on long trips when the battery temperature is already very hot. The theory is that a cold cabin, sitting directly above the battery pack, will increase heat transfer from the pack and help cool the pack.
Lemon Tea Leaf started out with a cool battery pack and then turned the AC on while the pack was fast charging. Lemon Tea Leaf compared the battery temperature rise with a Leaf that did not have the AC on. The battery temperature rise was about the same for the two Leafs.
In Lemon Tea Leaf's test the ambient temperature was about 60 degrees F and the average battery temperature was about 70 (60 with rise to 80) degrees F. 10 degrees F is not much of a driving force for heat transfer. When it's a 100+ degrees outside and your battery pack is already cooking on a long trip after several fast charges, turning down the cabin temperature while charging might make a signicant difference.
I actually tested this theory this last weekend. I drove almost 500 miles in my 2018 Leaf with four CHAdeMO charges. The goal of my trip was to test several battery temperature control strategies for long trips with multiple fast charges. The strategies were fairly successful, I really didn't start to see really high battery temperatures unit my fourth and last fast charge when the ambient temperature rose above 100 degrees F.
During the fourth charge I was just sitting there with a reduced charging speed and I thought about Lemon Tea Leaf's video. I turned the AC down and opened the hood to let the heat coming off the condenser escape. It's hard to say how much the cabin AC helped cool the battery pack but I have a feeling it helped keep my car from going into "turtle" mode when I finished this last hot, fast charge.
I don't thing turning on the AC while your driving helps, the moving air would just push out the cold air before it can have an impact battery temperature. But the bottom of the cabin is a large heat transfer surface and a heat transfer surface that is sitting directly above the battery pack and is 50 degrees F colder than the battery pack temperature has to create some kind of heat transfer. I think next time I try this theory I will start cooling down the cabin temperature 30 minutes before I start fast charging and I will be sure to bring along a sweater or jacket so I don't freeze myself out of the cabin.