Most states require that your HVAC installation be inspected by local authorities. This is not done simply to get the $50 fee from you, it is done like this to make sure your unit was properly installed and meets all safety requirements. In most cases, these safety requirements were drawn up at the expense of someone else s misfortune. Meaning… they want the gas lines to be installed correctly, because someone already paid the price of a gas leak explosion. They want the flue exhaust properly vented, because carbon monoxide kills.
The bottom line, is that your state may require your system to be inspected. If they do, they may also have a mechanism in place for you, the homeowner, to do the work yourself and request the inspection. You need to determine your own state or county guidelines first.
In addition to state regulation, the EPA has regulations concerning the handling of refrigerants in your existing system. In some way or another, almost all of the refrigerants are unhealthy to our environment and you can bet they are not good for your own lungs.