Problems with City Inspector on my first fixer upper

[John Baxter]

I've just bought my first fixer upper and feel like I've bitten off more than I can chew. It's an old wooden duplex in a nice neighborhood. I've been shocked by the poor quality tradesmen I've come across.
Now I have a major problem with a code inspector who has been knocking at the door claiming he's received reports of work without permits.
I have painted the interior, tiled the floor and done a few repairs which I don't think permits are required for- not sure though.
I paid an AC company to install central AC and I assumed they had all the permits required. I called them to check and they said they didn't have any permits so now I'm in a bad predicament.
I've been told it's best to avoid dealing with inspectors about anything and when they come to check off one permit, they will point out a bunch of other code violations you have to fix.
The inspector came once when I was at the property and I told him we just tiled and painted.
The neighbor told me he has come and knocked at the door and waited outside for hours everyday. Now I feel like I'm being harassed.
I have absolutely no idea what to do. I know they cannot enter your house without permission. I don't know if I just ignore him if he will go away. I have not received any letters in the mail. Can someone please offer some advice because this is my first rehab and I'm not experienced.