Running slow after plugging in the fan

You seams knowing about Mac i had a really hard question for you. I bought my MBP use and the first day i have it it was hot but really hot i was like it's maybe normal (it's my fist one) but 3 weeks later my friend told me that is actually not normal. So i look on internet and they talk about cleaning the Fan. So i start the process i open the cover and figure that actually the fan was unplug so i plug the fan back and now my MBP is so Slow and lagging it takes 17 minutes to boot what could be the problem ? ( the logic board, thermal paste, heatsink or the fan)