Molex style connectors were never meant to carry as much current as that. The connections are of a poor quality and your wires start to over heat. I suppose you could parellel your wires so that there would be 2 carrying the same current as one before. I am not familiar with your exact model but it seems you are not the only one to have the problem. I see this often at work on equipment not meant to survive the rigors of the factory floor. I have replaced connectors with high temp resistance. Ventilation also makes a diiference.
