The present invention is directed to a device, system and method for cooling a reagent compartment. The invention also relates to a use of the device. The device comprises a housing with a first side for attachment to the reagent compartment, a cooling unit with at least one cooling element with a warm upper side and a cold lower side, that is equipped with a cold side heat exchanger comprising at least one first fan, a at least one cold air channel and at least one cold air opening at the first side of the housing for circulating cold air between the at least one cooling element and the reagent compartment in a closed system.