Call Your Home Inspector and ask, they need to do some more explaining so you understand, that's what you paid for.
You are talking about a heat pump, which is using a forced air system to heat the house.
Give them a call and ask what it is you have. And any older systems will not be able to be updated without changing the whole system. The refrigerants have changed and system sizes have changed.
If you know the manufacturer you can google it and get the spec's.