Cooling Issue/Possible electrical issue

Ok so for the past 3 weeks my fiesta's cooling fan has been going on and off randomly for long periods of times, for example first thing in the morning before I'd start my car when I unlock my driver side door my cooling fan would turn on and run for about a minute...that's before I'd start the car. Once the car is running the cooling fan would be always on and once I'd shut off the car after my commute the fan would be running for a solid 2 to 3 minutes before deciding to shut off. So obviously after a couple days that issue never went away so I went to my local ford dealer and let them look at it and they couldn't find the issue that was wrong so they contacted the hotspot for further instructions on how they should proceed. So I had to wait for about a week till I went back at the dealership and during that second week my car decided to fix itself and the car was behaving fine...the fan would turn on if it felt it was getting hot and it would turn off of it wasnt needed. So when I brought it back to the dealership and told them what was up and how the car was fine they told me it was abit odd but if something comes up for me to keep them posted cause this is a new issue ford hasn't dealt with before. Sooooo now this leads me to tonight...as I was parked in a parking lot drinking a coffee with my car on running for 20min my car randomly started to overheat so I shut it off right away and let it cool down for 15mins. When I turned it back on and drove around the block for about 5mins the car was back to normal so like I'm not really sure what's going on with my car I think it has a mind of it's own cause it overheated that one time and now it's fine...so my question to you who ever read all this lol what should I do? Cause honestly I think I'm going to call this car Christine cause shes got a mind of her own and I dont know what to do even if i brought it to the car dealer cause they dont see anything wrong with the car cause it randomly fixes itself it seems. Thought?

Thanks for your time guys.

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