Northern Colorado is drier and its cooling season is shorter, so that specific number is not yours to claim. Where A Hot Second Floor Actually Comes FromWarm air upstairs is a symptom with a short list of causes, and they are not equally expensive. After that comes a slow refrigerant undercharge, which makes a system run longer for less cooling and shows up first as a utility bill that climbed with no change in habits. Back to the room upstairs. The table below sets one postponed season against one repair visit, using an ordinary second-floor office with two workstations and a NAS as the scenario.