Abstract: The invention relates to an absorption air conditioner that comprises a desorber (100), a condenser, an evaporator and an absorber, wherein the absorbing fluid may consist of lithium bromide. The method comprises the following steps: calculating the concentration of the absorbing fluid solution at the outlet of the desorber (100); and comparing the calculated concentration with a predetermined critical value and, if the calculated concentration gets closer to the predetermined critical value, increasing the charge loss in the duct (20) connecting the desorber (100) to the condenser, which interrupts the condensation in the condenser and results in a pressure increase in the desorber that stops the desorption and in a concentration increase, the charge loss being on the other hand reduced for resuming the desorption when the calculated concentration deviates from the predetermined critical value. The invention can be used in automobiles and absorption air-conditioners.