The invention relates to a method for washing cooling or air conditioning circuits, according to which a washing agent is conducted through said cooling or air conditioning circuit. Said agent dissolves and absorbs the soluble substances that adhere to the cooling or air conditioning circuits and discharges the mechanical contaminants. The washing agent is conducted through the cooling or air conditioning circuit that is washed in a closed cycle without escaping into the environment, by the pressure differential between the pressure chamber and the distillation chamber and is returned to the pressure chamber after being cleaned in the distillation chamber, compressed by a compressor and cooled in a condenser. The invention also relates to a device for washing cooling or air conditioning circuits, said device consisting of a pressure chamber containing a washing agent. The outlet pipe for fluid of the pressure chamber is connected to the cooling or air conditioning circuit that is washed. A compressor and a condenser, which is connected to a supply line for fluid to the pressure chamber, are connected upstream of said chamber. A distillation chamber is connected between the cooling or air conditioning circuit that is washed and the compressor and inert gas that is compressed by the washing agent is contained in the pressure chamber.