It has been my experience that you should always go through a professional for big renovations.
Usually we know somebody who knows somebody who can get you a good deal.
There are always plenty of local people ready to work, no question, but going the cheap route could cost you big time. A friend of mine got a local crew to do his roof, and they were cheap but not insured at all, so when his roof turned out problematic, it was tough luck for him. He had to call a professional to fix it! The same is true with HVAC work, don’t even let some uncertified yahoo poke around in your system because he says he knows what he’s doing. Let me tell you something, nobody has a regular job and also does HVAC work on the side. This job pays good money, so if you are certified and experienced with air conditioners and furnaces, then your regular job would be doing that, you follow me? If they are a cheap freelancer who claims to have AC experience, they are probably conning you. Even if they aren’t, I still wouldn’t let them mess with your HVAC equipment, just in case something goes wrong. Use a certified, licensed HVAC contractor or company, because they will stand behind their work in case there is an issue. It may cost you a few extra bucks, but it will be cheaper than paying a yahoo, and then having to pay the HVAC contractor anyway to fix the problems caused by this idiot.