Climate control not working properly

When using my climate control system my face and feet function works great, strong air coming out but when I turn it to defrost it blows very weak and blows on the feet too (even though it’s turned to defrost only) but when turned on feet it blows only on feet, and when on face it blows only on face. The fan works like normal but does seem to tone down when turned to defrost (like the sound just gets less) but still sounds like it’s blowing air forcefully.