Interesting. I have the same thing happens to mine occasionally. This has been going on about 4 years now. If I reset to the temp I want, it will generally hold that setting. Why it goes to 72 I have no idea, it seems to be a default setting. I will be watching for some of the A/C gurus response to your question. We have returned from a day trip already and found the cat curled up under pillows, because it got so cold when this happens.