help with fan heater wiring over heating

[cunniffe]

Hello. Can any one help. My blowers just cut out a few days ago. I traced it back to the motor above the front passenger footwell. I have replaced the motor and found that the electrical connector plug has melted in side the socket. It was the overheating that caused the problem not the motor itself. I've got the correct size fuse for the motor as well. Any one know why it is getting so hot? Cheers