R107 Heater Blower Not Working

A blower that stops on one speed, works only on high or is dead altogether is a common R107 fault. Before buying a motor, check the simpler parts of the circuit.

Symptoms and what they mean

• All speeds dead: fuse, relay, switch, motor or wiring.
• Only high speed works: the resistor or the switch contacts for the lower speeds.
• Intermittent operation: worn motor brushes, a poor connection or a failing relay.
• Noise or vibration: worn motor bearings or debris in the fan.

Fuse and relay

Check the blower fuse and its contact surfaces in the engine bay fuse box. Many R107s use a relay for the blower, and some later cars use a double contact relay. Swap with a known-good relay where possible. See electrical troubleshooting.

Switch

The blower switch on the climate control panel selects the speed. Using the wiring diagram, check that power arrives at the switch and leaves on the correct terminal for each speed. Worn contacts cause dead speeds.

Resistor

The lower blower speeds go through a resistor. If only high works, the resistor or its thermal fuse has probably failed. The resistor is usually near the blower housing. Replacement resistors are available.

Motor test

Feed the motor directly from the battery with fused jumper wires. If it runs strongly, the motor is good and the problem is upstream. If it is weak or dead, replace it.

Motor replacement

The R107 blower motor sits behind the firewall area, under the cover at the rear of the engine compartment. Removing the cover gives access. The general steps are:

1. Disconnect the battery.
2. Remove the blower cover and any components in the way.
3. Disconnect the motor wiring.
4. Remove the motor mounting fasteners and lift the motor out.
5. Clean the housing, check the drain, and fit the new motor.

Take the opportunity to check the area for rust and leaves. A blocked cowl drain can cause water in the blower housing, which kills motors. See drain holes.

Quick answers

• Can I lubricate a noisy motor? Sometimes it helps briefly. Replacement is the lasting fix.
• Does the blower affect the heater valve? No, but both are part of the climate system. See climate control and heater problems.
• Why does the blower work only with the engine running? That is normal on many cars with ignition-switched circuits.
• Is a blower failure common? Yes, especially on cars with old motors and blocked drains.