She clearly has some trouble with boundaries.. doesn't bode well that her behaviors towards you sound more like a dysfunctional mother's towards her child.

Summer's pretty well over in most of the U.S., but if you will still need an a.c. unit this time of year where you live, I would suggest assuring her you will use the unit as sparingly as possible, and remind her that she agreed to let you put one in. If it was me, that would be an absolute non-negotiable, but then my body has some inherent trouble with thermoregulation.

Otherwise, I would just keep my communications short and sweet with her. Smile and speak in platitudes to keep the peace, would be my advice. She sounds to me like she could be somewhere in the Cluster B construct, maybe a combination of borderline and narcissistic traits.. if it helps towards having empathy for her (especially at those times when you're more tempted not to), those traits tend to be the result of some fairly unfortunate (and in her case probably very well buried) childhood experiences. I would imagine the same holds true for ODD, though I don't have as intimate an understanding of that construct.

But I'd be keeping my eye out for a new place in the meantime.