A/C not getting real cold

Are you using a gauge manifold set? If so it sounds like it has a bad gauge. There should not be any pressure inside the gauge housing itself.

In the back of the gauge dial there is a metal scroll. One end connects to the fitting, the other is crimped and sealed and connected to the gauge needle through a few gears and shafts. As the pressure increases the scroll tries to straighten out. That motion moves the needle on the front. That scroll contains all of the pressure of whatever it is measuring. If it leaks the scroll is bad and the gauge is good for spare parts only.