There’s nothing more frustrating than weak air flow on a hot summer’s day! Unfortunately, there’s no easy diagnosis here; insufficient air flow could stem from a number of possible problems. For example, it might be an instance of mold or mildew building up in the evaporator core. It could also be a clogged cabin air filter. A bad blower fan or blown fuse . A qualified mechanic can isolate the root of your A/C problems.