Some noise from Joule or variation in motor speeds is typically no cause for concern, but we know it can be obnoxious/unsettling, so please try the following in order to troubleshoot:
1. Use the manual temperature setting mode to set your Joule to 20c/68f.
2. Wait one full minute and then observe whether the sound still appears to be happening.
3. If you still hear the noise, please let us know and we will move forward from there. If you no longer hear the noise, please follow the following steps:
a) Initiate a full cleaning of your Joule with vinegar.
b) Once the cleaning cycle is complete, check the inside of Joule by first ensuring that the foot of your Joule is cool, then removing the foot and propellor. Check to make sure the entire internal heater surface is clean and clear of any buildup.
Upon completing this check, please put the propellor back in place and screw the foot back on. This should resolve the issue! If it doesn't, please feel free to open a support ticket below and send along a video or audio recording so we can take a listen.