if you have no leak >? ac recharge will not do anything for cooling fan as far how it cools engine or stays on , ac is just to cool cabin inside , if you had problem before with cooling fan what you can have is normal for fan to stay up to 10 min after turn off that is in design it runs only when engine was running very hot . what is most common is the cooling fan module goes bad what is part of the cooling fan it self try replacing cooling fan
when is AC IS ON cooling fan can come on and off that is normal function. with ac also engine module can turn ac off on its own if it sees engine running hot . so I would try new cooling fan assembly that square box on cooling is module and is part of cooling fan also I would use new Volvo thermostat if not done so far .
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