Thanks for the question. It's normal for the microwave fan to turn on automatically as needed to cool the internal components of the microwave before, during or after use, and the microwave fan vents internally and through the front of the SMH1816.
If you don't feel that this explains the noise you're hearing, I would suggest checking with the person who installed the microwave to be sure it was installed correctly (including adjusting the blower motor so it's facing in the right direction for your venting) and all parts are sealed and secure. For additional support, please submit your contact information through the link below, or call 800-SAMSUNG to speak with an agent who will be happy to assist you.
Online support form: http://www.samsung.com/us/support/o...
- Ms. Samsung
answered 1 year, 6 months ago