Whilst updating the firmware on my P4 a couple of times now I've noticed that the cooling fan never comes on. The P4 gets very hot and then gives IMU errors due to maximum temperature being exceeded. I didn't even realise the P4 has a fan until last week when flying with my friend that has a P4 and the fan on his came on whilst we were getting ready to fly. I've never even heard the fan on my P4 come on! I'm a bit concerned that the fan is faulty on my P4?