A liquid filter/heat exchanger unit including a liquid filter and a heat exchanger, the liquid filter having a filter element in a filter housing. To bypass the heat exchanger, there is a bypass connecting the heat exchanger inlet directly to the unfiltered side of the filter element. A switching element is provided to control the liquid flow into the heat exchanger or into the bypass. The switching element is a bimetal element which is in a position directing the liquid flow into the bypass at a temperature below a switching temperature.