Would a bad FCM trigger a code? I don't want to order the blower motor resistor just yet as that seems like it's just an AC problem. My engine fan is also stuck on low besides the AC being stuck on low as well, not sure if the two are correlated. My "Low Coolant" indicator light is on as well but that is because I think I broke the sensor attached to the bottom of the coolant reservoir when I yanked it out to change the headlights, there is plenty of coolant in the reservoir.