This paper contributes to HCI with a foundation for exploring ways in which an Internet of Things (IoT) solution can support the maintenance of public automated defibrillators (AEDs) sustainably. AED is a critical lifesaving technology installed in non-medical environments. The technology places enormous demands on public engagement for its use and maintenance. Insights into how medical technology is maintained in non-medical environments can complement current innovations in lifesaving technology. This ethnographic study investigates the complexity around an IoT solution to remedy breakdowns in the maintenance of AEDs in a Danish context. We conceptualize maintenance as infrastructuring and identify how the diverse field of actors around an AED entails technical but primarily social dimensions revealing a controversy of responsibility and accountability. This article recommends that when developing an IoT solution for maintaining AEDs, technical, social, political, and ethical dimensions should be considered to address responsibility and accountability issues.