Example embodiments described herein involve reducing the formation of ice on external modules by incorporating a heater within the module. The system may include a microphone module for an autonomous vehicle. The microphone module may include a housing and a microphone inside an opening of the housing. The system may further include a cover abutting the opening of the housing. The cover may enclose the microphone within the housing and seal the opening of the housing. The system may also include a heater adjacent to the opening of the housing and configured to prevent ice from forming over the opening. The heater may at least partially surround the opening.