Rattling when A/C on in van?

I have a 2005 ford freestar and recently had some bolts replaced on the tranny pan. I never heard a rattle before, but now when the A/C is on, I hear a rattle. This girl can not go without A/C and my husband "mechanic" never takes me seriously when an issue arises with my car! I plan on sticking him with whatever bill may come out of this so im not worried about price! Thanks!!