Thanks for posting back. Without a doubt there are a lot of jokers on this forum, but there is also a lot that treat it like a family.
I mentioned the feral cat with a little tongue in cheek, but there is a certain amount of truth in it also. Some parks have a lot of cats that roam around and like to spray new rigs. Cat pee smells just like ammonia. Maybe even the prior owner of your rig had a cat and with the dampness that smell is coming back.
The only thing that uses ammonia is your RV fridge and there has been issues with them catching on fire recently. So that is why everyone is telling you to keep an eye on yours. While you're at it, check your smoke detector to make sure the battery is good. Many disconnect them because they go off every time you cook, make sure yours isn't one of them. :)