Hi @xiibkaushik2807
It may be a faulty fan or worst case is a faulty fan control circuit on the motherboard.
As there are two sensors on the fan itself, a temperature sensor and a speed sensor, maybe try replacing the fan first and check if that resolves the problem.
Here's the [https://dl.dell.com/topicspdf/vostro-14-5415-laptop_owners-manual3_en-us.pdf|service manual] for the laptop. Go to p.30 to view the procedure to remove/replace the fan.
Search online for ''0KRK6P'' to find fan suppliers that suit you best.
If the same problems occur with a new fan you will need to find the schematics for the motherboard.