Hi Rtcfrtc1950.
Thank you for reaching out regarding your Samsung - 30" Single Wall Oven with Flex Duo, Steam Cook, and WiFi; if this is a convection oven and if there is an option to switch off the fan. Regarding your concern, this is a convection oven, and the fan will automatically shut off when the door is opened
I suggest you check this link to your user manual for further assistance. Please go to page 33.
https://downloadcenter.samsung.com/content/UM/201904/20190417153210498/NV51K7770S_AA_DG68-00857A-03_EN-MES-CFR.pdf
Also, here is the link for the full specs, dimensions, and features.
https://www.samsung.com/us/home-appliances/wall-ovens/single/nv51k7770sg-aa-nv51k7770sg-aa/#specs
Should you need more assistance, please feel free to get back to us via the following options:
1. Facebook Messenger: http://m.me/samsungsupport
2. Twitter: https://twitter.com/messages/compose?recipient_id=18768513
3. Samsung Community: https://us.community.samsung.com/t5/Samsung-Community/ct-p/us
Thank you for being a valued customer of Samsung. Have a great day.
Reference Ticket Number: 1144398986
^Camille