Receives a 12V signal when the truck ignition is turned to the "ON" position.
Connected to a 30A fuse (typically F2 in the Power Distribution Module/PDM). This wire is often Light Blue (LT BLU) or Red . Freightliner M2 Blower Motor Wiring Diagram
Heavy-gauge 12V constant power from the fuse panel. Pin 2 (Ground): Heavy-gauge chassis ground line. Receives a 12V signal when the truck ignition
The ignition switch triggers the HVAC relay in the PDM, sending 12V battery power directly to the blower motor resistor/module and the dash switch. Freightliner M2 Blower Motor Wiring Diagram