2003 Pontiac Grand Prix blower

We have a 2003 Pontiac Grand Prix with the usual leaking cowl problem which causes the blower motor wires to short. I caulked around the rubber gasket on the cowl and had the blower resister replaced about a year ago. The problem has returned, only worse. Not only does the blower not work, so there is no heat or AC but now the car will sometimes (erratically) just not start. I went to replace the resister myself and discovered that the shop that had done the previous job had caulked the resister into place. And, of course, the resister is behind the AC unit against the engine firewall, making access difficult. I ended up unplugging the resister, leaving it in place and plugging in the new one. However, this did not fix the problem(s) this time. I suspect the wiring issue has grown and will need to be traced. Any thoughts?