Power steering pump 1992 Ford Clubwagon

Recently my power steering pump in my 92 ford clubwagon with 140000 miles has started leaking like crazy. The fluid is just pouring out and I can't figgure out why. We had the whole thing gutted and redone, seal and parts of the pump, this summer. Now about 8 months later its just started leaking after a normal trip around town. It has been very cold lately here in st. Paul mn, about -10 at the time of the start of the leak. I am wondering if the cold could have made it leak? Also I have a teenage son who just started driving and I am wondering if there was anything he could have done to break it? How could I fix it and would it just be cheaper to put a new one in my self? Thanks much.