Why would my power steering pump go out after replacing my harmonic balancer?

I have a 2000 Chevy Venture van and recently paid almost $300 to replace the harmonic balancer and serpentine belt. Now, less than 2 weeks later, it sounds and acts like the power steering pump is out. (Loud screeching noise, worse when the steering wheel is turned, hard to turn, and the power steering fluid reservoir is full) Can I ume they have something to do with each other? Is it probable the mechanic did something wrong?