My air conditioning stopped working after perhaps two operating hours. I could cycle through the modes but the Temp Up/Down buttons were non-functional. A service tech determined there was dirt, moisture or both in the foam padding just behind HVAC control pad cover. After removing the cover, the buttons could be pushed normally and the air conditioning worked fine. Cleaning the foam (by compressing and blowing on it) restored full function. I did not notice this problem or fix on the forum so I offer it here. Hope it helps someone.