I kegged two batches of IPA, one two weeks ago and another 1 week ago. Both are only lightly carbed. I have them in a fridge at about 40 degrees, and gas is set at about 12.5. Any thoughts, or should I just wait longer?
Sounds like your doing the 'set it and forget it' method, (which is what I do). I usually takes about 3 weeks before the beer is carbonated. 2 weeks....should be lightly carbed. Sounds like you are doing fine.
Yeah, give it a little time. And if it is still undercarbed and you still have gas, bump it up a psi or two. You will soon discover what level you prefer.
I did this a few weeks back and also got worried after two weeks without a fully carbed beer. I shook mine a little (nothing crazy, just to splash it). The next day it was good to go. It may have been a coincidence or may have helped it carb up. I just thought I'd share.