High temperatures pose great threats to the health of urban populations. The use of air conditioners (AC) is an important adaptive means to reduce the morbidity and mortality of heat-related diseases. However, it remains unclear how exposure and sensitivity factors affect residents' AC use. This study aimed to answer this question through a case study in 78 residential areas in Beijing, China. We conducted over 7,000 structured interviews during June 20-August 5, 2017 to learn respondents' AC use, health conditions and socioeconomic status. We also used remote sensing data to obtain land surface temperature (LST) and proportion of greenspace in residential areas. We applied a multilevel logistic regression to assess the influences of these factors on probability of frequent AC use. The results showed mixed impacts from sensitivity factors on AC use. While respondents with chronic diseases were 14.7% more likely to use AC every day, probability of AC use decreased by 29.2% with the increase of age groups. Instead of economic cost, the main reason preventing respondents from using AC was "feeling uncomfortable" or consider it as "unhealthy". At the scale of residential area, results did not find significant impact of LST on AC use, while proportion of greenspace posed a negative impact on probability of using AC every day even when LST was considered.