Very often the problem with the operation of air conditioner on the Mercedes S-class (W221) is connected with depressurization of the system. Service centers usually insist on replacing the system dryer. This is done for the next purpose-if the depressurization occurred long ago, there was a lot of air in the system that contained a certain amount of moisture. Since the task of the dryer is to absorb moisture from the refrigerant, it absorbs the water contained in the air. Since there is much more of it than in the freon, there may be a break in the bachka, which will entail costly repairs to the entire system. Therefore, if the exact time of occurrence of a leak is not known, then the tank should be replaced. If the repair is performed immediately after depressurization, the replacement of the bachka is optional.