Control unit, ventilation fan, MCC (220a): Connection

The control unit has one connector which is connected to the MCC unit and two separate outputs for ventilation fan motor power supply and ground.

Four pin connector.

Fig 1: Identifying Communication Flow - Ventilation Fan Control Unit (MCC)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Control unit B+ feed to pin 1 from fuse 23 (fuse board 22) and ground connection through pin 3 on grounding point G41.

From MCC unit pin 27, fan speed is controlled by control unit pin 2 with 0-5 volts.

The ventilation fan motor is connected with 2 separate inputs from the control unit.

The fan motor is connected to ground on pin 2 through the fan motor control unit on grounding point G41.

The fan motor receives current on pin 1 and the speed is controlled by the control unit through an increase or decrease of the power supply.

Wiring diagram, control signal.

Fig 2: Circuit Diagram - Ventilation Fan Control Unit (MCC)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Wiring diagram, power supply.

Fig 3: Circuit Diagram - Ventilation Fan Control Unit (MCC) (Power Supply)

Courtesy of SAAB-SCANIA OF AMERICA, INC.