Ice Air VRF ODUs incorporate an advanced oil control system to ensure proper oil balance between compressors within each ODU/module and the proper oil balance between all modules. An oil accumulator uses porous oil return technology with a built-in fine strainer. The oil control system implements a 60-second oil-return operation based on compressor frequency and operation time. This oil control operation can be implemented in either cooling or heating mode, ensuring seamless operation during the oil control cycle.