Why doesn’t the Fan blow as hard anymore

Hello, if all vent registers are confirmed to be in the open position, and you don't have enough air flow, it sounds like you may have a mode door concern, which is directing air flow into the wrong location. Some inspection and testing is needed in the climate control system to see what is happening there. Yes, there could also be a blower motor concern, perhaps not producing enough air, but it sounds more like the direction of air flow first. www.repairpal.com/repair-shops