I don't know how PF does their hot water limit control, but all new valves have some means of preventing the handle from allowing the water to get too hot. Part of the install instructions tell you how to set and adjust that limit. This could be a screw, a cam, or some other thing. It may just be that that is adjusted such that you can't get very hot. Often, if you have really cold water in the winter, and you've adjusted the thing properly in the summer, it won't be hot enough for those who like it really hot because the limiter won't allow enough hot to come through. SO, you have to figure out how to adjust it, and then, only after you've adjusted it to provide more hot, can you determine if there's a fault, or it's just an adjustment you need to figure out.