Try to find an expert you can trust. If you can't an option is: What happens many times is that the dust on the cooler blades does not let the cooler spin. Many computer stores sell compressed air cleaners. Since it contains compressed air and air is not a good conductor of electricity it will not harm your circuits even if it is in a liquid state; any drop of air will be converted into gas state air immediately, there are risks like the change of temperature but a tiny drop should not dramatically harm.
DO NOT SHAKE the compressed air cleaner and then apply it (do not apply it upside down or it will be a very cold liquid). It is beneficial to apply compressed air periodically to prolong the life of the computer and do not let the dust to be accumulated and become a block. The compressed air cleaner always needs to be applied when the computer
is off. Dell notebooks tend to over heat even if the cooler is clean.
I am not an expert in repairing computers but this has been beneficial to me. You should apply it near coolers, in some cases it can be done without disassembling the computer.
Sometimes the dust is abundant and the compressed air cleaner is not enough:
http://www.mejor-ant...limpiar-pc.html
Cleaning MacBook cooler system:
https://www.youtube....h?v=ABs0L2VpLuA