I am currently writing a short story during which my characters spend a decent amount of time hiding in a vehicle repair garage (that typically repairs SUVs) shortly after it has been abandoned in the middle of a work day. I like the idea of using background noise to create tension in a specific scene but I have no clue what sort of machinery would give off any kind of sound whilst unattended. My specific questions are, what sort of machinery is typically present in this environment? What sort of machinery could potentially be left switched on if everyone was forced to flee abruptly? And what other sorts of sounds could be expected in this environment with no people around? I don't intend to use specific machine and electronic names within the story, but they would be helpful in giving me an idea of the ambience of the place. If anyone has any resources or experience relating to this your help would be much appreciated!