If your air conditioner isn't blowing as hard as it used to, you likely need to clean out the evaporator. It's located behind the glove box and this is an easy way to clean it without having to pull the dash.
Should be the same method for all Ford F250 and F350 trucks 2011, 2012, 2013, 2014, 2015, and 2016. Not sure what the newer trucks are like. Only warning would be not to cut too deep when cutting into the air box. Good luck with your repairs!