I look at it this way. I "could monkey with it, not knowing what I am doing and totally FORK it up so the next hot spell is a "Visit to Hell"..or, I could take it to a shop that SPECIALIZES IN R.V. A/C and pay them to fix it.
. As it only sat there unused, then it must be something simple...right? That is how they are built. So FAULT YOURSELF FIRST. You forgot to do something...most likely. Something simple.
Or,or,or...a radical idea would to read the operators manual. They print those books just to waste time, paper and ink...or they HAVE THE ANSWER.
I know I am pushing the envelope here but some people never read instructions....think they know everything when they PROVE they know nothing. You might know some people like that.