Sunrooms, three-season rooms, and similar glass-heavy spaces create a unique load that central air systems were never designed to handle. Large amounts of glass allow significant solar gain. Even with blinds or low-E coatings, the space can heat up far faster than the rest of the house. The main system responds to the thermostat in the living area, not the sunroom. By the time the central unit runs long enough to pull the temperature down, the rest of the house is overcooled