Converting air conditioner ducted to ductless

Hi, just read your post and thought adding an opinion in since we deal with ducted reverse cycle air conditioning installations regularly. From what you described, it does sound like your previous unit was part of a ducted system, where typically one duct serves as the return air and the other for supply (blowing cooled air out). Simply sealing them off with cardboard and tape might work temporarily, but it’s not the most efficient or recommended solution, especially if airflow balance or insulation is a concern. In our experience, when converting from ducted to non-ducted, it’s important to properly seal or repurpose the existing ductwork to avoid energy loss or unwanted air pressure issues. If you are not using those ducts anymore, having them professionally sealed can help maintain overall system efficiency and comfort. Always great to see people diving into their own installs. Hope it all works out smoothly!