Hi RitaGomes2,
Thank you for raising this concern of yours here in Microsoft Community. We apologize for the inconvenience this has caused you.
It's basically normal for the Surface Pro 7's fan to kick in when there are several applications that are still running in the background with high CPU usage. Those were definitely the reason behind the loud fan noise and to check if there's anything else that triggers the performance of the Surface device, what I'd like you to do to troubleshoot this issue is to run the system file checker to check if there are corrupted system files that are just looping around causing this issue to exist. To run the system file checker, kindly type Command Promp****t on the search box next to the Windows icon and run it as administrator. Once done, type and enter sfc /scannow. Let it load, detect and repair those corrupted files. Whether it detects a corrupted file or whatnot, kindly restart your Surface device and please run the Surface Diagnostic Toolki****t and make sure to set the device battery performance to recommended, making the device to run just fine without the need of a fan or with less assisted cooling needed.
If in case there's nothing in Task Manager that runs with high CPU usage and the issue still exists, you may have to reset the device back to its factory settings. So, please save all your files first before doing the complete reset.
If this helps, feel free to mark this post as an answer. Otherwise, don't hesitate to contact our Microsoft Surface Support to get further assistance in getting a replacement for that unit.
Kind Regards,
Crest_Z