A/C Blower Motor is good but doesn't work 2000 Signature Series

My AC went out on my 2000 Town Car a few years ago. I'm sorry I can not recall the actual component but, it was small and it costed approximately $50. My mechanic (not the dealer) identified it by plugging in his diagnostic machine; he called up a schematic on his computer and showed me the part, wrote it down, sent me to a Ford dealer to get the part. It only took him a few minutes to replace it. I remember the guys at Firestone had no clue; they swore it was the fan; replaced it and when that did not work; they put the old one back on and I took it to my mechanic who took care of it quickly and for less than a $100. I will see my mechanic next week and will ask him and post what the part is.