Does mini split HVAC require a permit?

Hi, I have what I believe is n expired permit, for work we couldn’t afford to do. It does not mention HVAC specifically — do I need a permit to install 7 wall units and 2 outdoor condensers, one in front and one in back but neither on the roof or anything tricky — and what dependencies would this have? what WOULD trigger needing a permit? I’m in a wood frame attached house, no historic zoning or anything. Thanks!