A/C Heater Blower Problems

[Bennydog]

Hello I have a 75 C10 with heater and air conditioning. RPO C60.. My heater was not blowing so i decided to fix it. got new relay, resistor, blower motor, and switch inside. It runs when key is on in low like it should. It works in low medium 1, and medium 2. But blows fuse in High. I have checked all grounds and jumped ground to fan and it works fine. I noticed this 2 connector under the relay, and sure enough when i unplug it it does not pop the fuse and just goes back to low speed when high is selected. When i put a light on the connector the orange wire gets power only when high speed is selected. so i unbolted it and it has one wire running through the heater core.. WHAT the hell is this thing... Please help!