The Humhold 12000 BTU Portable HVAC (and similar window vented portable HVACs) do not have a damper system and hence allow hot air from the outside to come back into the room when the unit is off. This damper mounts to the exterior of the vent hose's window mounting plate.
Link to unit:
https://www.amazon.com/gp/product/B0D9GNY44T/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
| Base.stl | 311.8KB | |
| CE3E3V2_Base.3mf | 129.7KB | |
| CE3E3V2_Flapper.3mf | 190.4KB | |
| Flapper.stl | 263.9KB | |
| Humhold_HDPAC-08-A1_Damper.f3d | 284.3KB |
