Apparently odors are really tough to get rid of in boats.
Not really if you know what works and--most importantly--how to use it. And since you, along with several others are fairly new around here, I prob'ly need to say again that I'm not in any way associated with any product or equipment manufacturer, nor do I receive any compensation whatever for recommending any product or manufacturer. My opinions are my own and my recommendations are based on my own experience and that of boat owners over several decades. And I've included most of it in my books (see link in my signature).
Now that we have that out of the way.....
There's a product called PureAyre
PureAyre that will get rid of every trace of the residual odor in your fridge(fwiw, the same thing happened a couple of times on my own boat) ...it even eliminates diesel and smoke odors...and it's rated for use around food, so it's safe to use in your fridge. Amazon has it...so do pet stores...Walmart may have it. If you only have to treat the filters and the fridge, you prob'ly only need the spray bottle size, although it can't hurt to have a gallon hand 'cuz you'll never know when you'll need it again. It's the best thing I've ever found to get rid of any residual odor. The "household" version is the least expensive and works just fine on boats.
Assuming that you've already thoroughly cleaned every surface, nook and cranny in it, take everything out of it and spray PureAyre onto every surface, nook and cranny in the freezer and door too...don't just aim it at the inside of the fridge, carefully coat every milimeter of it with a fine mist that coats everything..Then prop the door open so air can circulate and let it dry overnight. Wipe it all down with a clean damp rag and stick your nose in...if you can smell anything, you missed a spot.
I don't know whether your HVAC filters can be saved or not...but you have nothing to lose by spraying those with PureAyre too. Again, cover every square milimeter from both sides, then put 'em outside in the fresh air to dry. If that doesn't work, you'll have to replace the filters.
Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein