CO2 and the right type of air conditioner

I want to add CO2 to my grow room, however my understanding is that most AC units (like the one I have now) exhaust air out the room to keep the compressor coils from adding heat in the room. This defeats the purpose of adding CO2 because it will just keep getting pushed outside.

My friend has a mini-split that is designed to not exhaust any air but it cost him like $3k, I cannot afford that. Internet research does not say much about which AC units don't exhaust air. Can anyone point me to the types of AC units that I need to run CO2?

Dual hose portable.

I'm not sure if this will effect your decision to use CO2 or not but I just thought I'd put it out there just in case.

Mini split is the best, if your'e good with framing you can use a window shaker. I haven't used a portable but my friends did not like them. Look at SEER & energystar ratings.