2003 Cadillac Deville Auxillary Blower Motor Resister

Within the last couple of weeks our a/c blower has been cutting out on us. The a/c is working but the blower is not blowing. We will go over a bump and it will come on. It has gotten gradually worse each time we go out and with the heat in the 95+ degree range, it gets rather hot while we look for bumps to go over. We went to an auto parts place today and were told it is most likely the Auxillary Blower Motor Resister going bad. We bought one but do not know where to find where to replace it at. The manual we have does not show where it goes. We have tried to find it on the internet but only get vague info about "behind the dash". Could you tell us where to locate the place to replace this at? Thank you.