A method of monitoring a heat exchanger arrangement is provided. The method includes detecting a rotational speed of a ram air fan configured to draw air through the heat exchanger arrangement. The method also includes detecting a power input from a motor to the ram air fan to maintain a commanded rotational speed of the ram air fan. The method further includes comparing the power input detected to a predetermined power limit for the commanded rotational speed. The method yet further includes decreasing the rotational speed of the ram air fan with a controller if the power input detected exceeds the predetermined power limit.