normal behaviour 2016 fiesta engine fan

[Greycar]

hi, i've seen a fiesta i want to buy, 2016 1.25. the fan seemed to run constantly. it also ran for a little while after the engine switched off. we were told when we asked about it afterwards that it was caused by the aircon (or demister) being on. i will check on going back that it does not come on when engine is started form cold and aircon and demist are off. please can some one who knows these cars tell me when it is normal for the fans to come on. thanks