Heater Fan not working on Position 1
Depending on the position of the blower motor switch, the blower motor is off or operates at one of four speeds. In the 'off' position, the earth side of the blower motor is open circuit. In position IV, the blower motor is connected direct to earth on the B wire between the blower motor switch (C0058) and the earth header (C001 7). In positions 1 to Ill, the blower motor is earthed through the resistor pack, on one of three wires to the blower switch, and the B wire from the blower switch to the earth header:
With the blower motor switch in position 1, the earth is routed through 3 resistors in series in the resistor pack (C0425) and connected to the blower motor switch (C0058) by a KB wire.
With the blower motor switch in position 11, the earth is routed through 2 resistors in series in the resistor pack (C0425) and connected to the blower motor switch (C0058) by a YB wire.
With the switch in position 1 1 1, the earth is routed through a single resistor in the resistor pack (C0425) and connected to the blower motor switch (C0058) by a GB wire.
For the Heater Blower Circuit Diagram, see below.
The resistors are actually coils of resistor wire that are designed to be kept from overheating by always being in the flow of cold air taken into the heater.
However, if the airflow is reduced, possibly by leaves entering the intake box, snow over the air intake panel, or maybe simply with all vents turned off, the reduced air flow for any prolonged time may not be enough to stop the resistor from glowing and burning.
Looking at the above photograph, the nearest and thinnest wire measures 2.1 ohms, the tallest is 1.5 ohms, and the one at the back and thickest is 1.0 ohms.
The usual problem is that it is the third resistor coil that burns out and this is the one that effects the lowest fan speed.
The options are to replace the Resistor pack with a new one - Rover Part Number: JGM100060 at £ 25.50 inc VAT in August 2005 - or to try and repair the burnt out coil.
UPDATE: There is now a company selling a replacement kit of resistors for the
d.i.y. repair, rather than replacement of the whole unit.
Have a look at REZPAX.
It's much cheaper, and the website also has downloadable instructions.
Removal and Repair:
Empty the glove box, so as not to strain any of the fastenings.
Undo and remove the two screws on the front face of the box.
Unfasten, but do not remove, the two screws underneath the glove box. Leaving the screws in place will make it much easier to refit the box.
You can now slide the box nad these two screws off the locating holes, but be aware that the glove box light wiring is still attached, so you cannot move it very far.
Remove the light and switch connectors.
Undo and remove the nut that holds the right angled air duct. The duct takes the incoming air from in front of the screen down in to the heater module, and simply locates into the holes at either end.
Remove the air duct.
Disconnect the multiplug from the resistor pack, and remove the two screws securing the resistor pack to the heater module.
Remove the resistor pack.
You can see where the third resistor on mine has overheated and broken. It's very difficult, if not impossible to re-solder the broken ends, but if you can get hold of similar resistance wire, it should be possible to replace the whole resistor with a similar coil and a resistance value of about 1.5 Ohms.
If there is any dirt on the other coils, carefully remove it to ensure there is no localised overheating.
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Heater Blower Circuit Diagram