A system for heating or cooling a fuel cell circuit of a vehicle includes a fuel cell stack, a temperature sensor to detect a fluid temperature of the fluid, a pump to pump the fluid through the fuel cell circuit, and an ECU. The ECU is designed to determine a temperature control signal based on the fluid temperature of the fluid. The ECU is also designed to calculate a desired mass flow rate of the fluid through the fuel cell stack based on the temperature control signal. The ECU is also designed to calculate a desired pump speed of the pump based on the desired mass flow rate of the fluid through the fuel cell stack. The ECU is also designed to control the pump to pump the fluid at the desired pump speed to increase or decrease the fluid temperature of the fluid.