[GTP Dad]

This sounds like a reasonable explanation for the problem you indicated. Usually fuses will only blow if there is a problem in the electrical system that is causing an overdraw of current. If the AC control unit is bad this could indeed cause the problem. As far as the cost to repair that is reasonable although that may just be for the part. I would get a true quote from the mechanic to see what his labor charges are going to be. This could end up costing a lot more money if you fail to pin him down.