Removing the controller wasn't that difficult once I removed the block to heater core hose. I didn't have any trouble with the mounting screws I just used a long 8mm 1/4 inch socket wrench. The round "thing" that goes inside is a TO-5 transistor mounted on a heat sink, this is what actually regulates the amount of current that is delivered to the blower motor. The EATC outputs a variable voltage that corresponds to the blower speed required this feeds the large transistor thus speeding up or slowing the blower speed. As the blower speed increases more current passes through the transistor thus generating heat, by mounting inside the air input housing the air flow helps keep the transistor cool.
