May 132017
 

1997 Dodge Ram 1500My air wont blow thru vents


Either your vents are blocked, disconnected or the blower motor is not coming on. If it is the blower motor that is not coming on at all you may need to replace the blower motor and or the blower motor resistor.

If you find the blower motor working, the temperature blend door actuator  or the door itself may be at fault.

BLOWER MOTOR

When the ignition switch is in the RUN position, circuit C11 from the blower motor relay provides voltage to the blower motor.

From the blower motor, circuit C7 splices to the blower motor resistor and the A/C-Heater control switch.

The ground path for the blower motor is through the circuits that connect from the blower motor resistor block and then through the fan switch in the A/C-heater controls to circuit Z3. The blower motor resistor block consists of three resistors connected in series.

Each resistor in blower motor resistor block is spliced to the fan switch on separate circuits; C4, C5, C6, and C7. Depending on fan switch position, voltage passes through one or more resistors to ground. Blower motor fan speed is controlled by the number of resistors voltage passes through to ground.

When the fan switch is in the LOW position, circuit C4 provides the ground path. In the M1 position, circuit C5 provides ground. In the M2 position, the ground path is through circuit C6. Circuit C7 provides path for ground when the switch is in the HIGH position.

BLOWER MOTOR RESISTOR

The blower motor resistor is mounted to the heater-A/C housing, under the instrument panel and just inboard of the blower motor. It can be accessed without removing any other components.

The resistor has multiple resistor wires, each of which will change the resistance in the blower motor ground path to change the blower motor speed. The blower motor switch directs the ground path through the correct resistor wire to obtain the selected blower motor speed.

With the blower motor switch in the lowest speed position, the ground path for the motor is applied through all of the resistor wires. Each higher speed selected with the blower motor switch applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed. When the blower motor switch is in the highest speed position, the blower motor resistor is bypassed and the blower motor receives a direct path to ground.

The blower motor resistor cannot be repaired and, if faulty or damaged, it must be replaced.

 Leave a Reply