NOVELTY - The functional module (1) has a container (3) having an ion-exchange material, and a pump device (2) for the coolant which are fluidically coupled to each other in such a manner that the coolant inlet and the coolant outlet of the pump device are connected to the coolant outlet and coolant inlet of the container. The container surrounds one region of the pump device, which comprises a conveying unit of the pump device in some regions around the outer circumference.    USE - Functional module for coolant circuit of fuel cell system mounted in vehicle.    ADVANTAGE - The container containing the ion exchange material surrounds the outer periphery of conveyor unit, so that cooling of the pump unit can be ensured, and heat is removed through the coolant which flows through the ion exchanger material. The proper cleaning of the coolant and high functional reliability can be ensured. The complementary design can ensure that only the appropriate container at the delivery unit and the pump unit fits around. Since there is a very high pressure difference between the refrigerant inlet of pump unit and the coolant outlet of pumping device, the more uniform flow or good flow through the entire ion-exchange material can be ensured by parallel connecting of the ion exchanger material having container at coolant inlet and coolant outlet of the pumping device. The container is simple and can be mounted quickly without brackets, and even at the typical driving vibrations, the container is securely held in the pump device. The large surface contact between the delivery unit and container is ensured, which results in operation of refrigerant circuit to good cooling. The tight-fitting fluidic coupling of the container and pump unit is enabled, so that the container is well protected against environmental influences. The avoidance of access of moisture to the ion exchange material which prevents aging is achieved and thus long period of storage before use of container in the coolant circuit is enabled. The optimal functionality of the ion exchanger is permanently guaranteed. The pressurizing element can be designed in the manner of a spring which prevents the ion exchange material in the volume occupied by a void volume. The closing element ensures that no loose ion exchange material can be introduced in bulk or in bags or wrapped like ion exchanger in the coolant circuit. The use of self-sealing interface at the coolant inlet and coolant outlet of container and/or the length of pump device can be reduced by connecting tubes.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for manufacturing functional module.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of the functional module.    Functional module (1)    Pump device (2)    Container (3)