Suggest you try different brands of filters. I tried at least five different ones (just the intake filters, not counting the hepa filters that i tried). I have a very good HEPA filter for those inside cabin (refer to my post), so I don't need a super thick intake filter. Avoid getting filters from taobao, if you get it locally, odds are it is still taobao. They don't work well. Go check out youtube reviews. I am using stuff I ordered from Amazon US. I never had problems with filters from overseas. Even on auto, my fan never gets above four (since oct 2020 till now). I usually find it too strong, and set it back to two. Basically, I don't have any noticeable difference in fan settings. Bear in mind, I monitor based on my comfort level, not how strong the air is blowing in my face. I usually don't direct air flow directly to me at all. Overall, makes a huge difference. I rarely have to wipe away dust inside my car. Good luck