Heater Blower - Fresh/Recirculated Air Motor Operation

Heater Blower Operation
The speed of the front blower motor is controlled by the blower motor switch position and three resistors located in the resistor pack. The blower motor will only operate with the ignition switch in position II.

With the ignition switch in position II and the blower motor switch in position 0 (off), the earth path for the blower relay coil is not complete and the relay coil cannot energise.

When the blower motor switch is moved to position 1, 2, 3 or 4 the blower relay coil is connected to earth on an N wire to the blower motor switch. The blower motor switch is connected on a B wire, via splice joint A7, to earth eyelet connector C0910-1. This causes the blower relay coil to energise closing the relay contacts.

With the relay contacts closed, the feed from fuse 7 in the passenger compartment fusebox passes through the relay contacts to the front blower motor.

With the blower motor switch in position 1, the earth path for the motor is via the resistor pack, through the 40 Amp in-line fuse and the three resistors (0.32/0.85/1.71 ohms) which limit the power flow to earth and operate the blower motor at slow speed. The resistor pack is connected on a B wire, via splice joint A7, to earth eyelet connector C0910-1.

With the blower motor in position 2, the earth path for the motor is via the resistor pack, through the in-line fuse and two resistors (0.32 and 0.85 ohms) which limit the power flow to earth and operate the blower motor at slow/medium speed. The resistor pack is connected on a PU wire to the blower motor switch. The blower motor switch is connected on a B wire, via splice joint A7, to earth eyelet connector C0910-1.

With the blower motor switch in position 3, the earth path for the blower motor is via the resistor pack, through the in-line fuse and through one resistor (0.32 ohm) which limits the power flow to earth and operates the blower motor at medium/fast speed. The resistor pack is connected on a G wire to the blower motor switch. The blower motor switch is connected on a B wire, via splice joint A7, to earth eyelet connector C0910-1.

With the blower motor switch in position 4, the earth path for the blower motor is direct to the blower motor switch on a BO wire via splice joint A1 and operates the blower motor at fast speed. The blower motor switch is connected on a B wire, via splice joint A7, to earth eyelet connector C0910-1.

Fresh/Recirculated Air Operation
The fresh/recirculated air mode motor can only operate when the ignition switch is in position II. The feed from fuse 31 in the passenger compartment fusebox is connected to the fresh/recirculated air switch and the fresh/recirculated air mode motor.

Fresh air position
When the switch is in the fresh air position (latched out, indicator lamp off), the feed from fuse 31 on a GK wire cannot pass through the indicator bulb to earth due to the switch position

The air mode motor is connected on an UB wire to the switch. When the motor reaches the end of its operation to move the fresh/recirculation air flap, an internal switch in the motor moves ready to accept a feed to move to the recirculate air position. While the motor is operating it is connected through the switch on a B wire, via headers C0725 and C0760 to earth header C0017 LHD/C0018 RHD.

Recirculated air position
When the switch is in the recirculate position (latched in, indicator lamp on) the feed from fuse 31 can pass through the indicator bulb which illuminates and flows through the switch contacts. The switch is connected on a B wire, via headers C0725 and C0760 to earth header C0017 LHD/C0018 RHD.

The air mode motor is connected on an RG wire to a diode and from the diode to the switch on an RU wire. When the motor reaches the end of its operation to move the fresh/recirculation air flap an internal switch in the motor moves ready to accept a feed to move to the fresh air position. While the motor is operating it is connected through the switch on a B wire via headers C0725 and C0760 to earth header C0017 LHD/C0018 RHD.