I've been driving 12 years and it seems like I've never had an AC system that has always run perfectly. The current issue is it will seem like it's working okay but as I'm driving along it blows less and less powerful. I turn off air circulation and then it will possibly start blowing harder sometimes I will turn the AC off with the fans all the way up and it will again start blowing harder at which point I turn AC back on. During the night the AC blows less and less both in the cab and the bunk until it's hardly blowing at all but you still feel cold air. The blowers are fine and the cab one was replaced about a week ago.