What does a blower motor regulator do?
The Blower Motor Regulator controls the speed of the blower motor in your vehicle’s heating system. The regulator consists of a set of three resistors or terminals that generate a voltage to vary the speed of the motor. Each speed setting of the fan causes the current to flow through a combination of the resistors.
How does the blower motor resistor work?
Blower resistors are resistors which are used to control the fan speed of automotive blowers. The fan speed can be changed either by switching the blower resistor resistance mechanically using a rotating lever, or electronically by the air conditioning system.
How to test a Mercedes Benz fan blower motor regulator?
This is the blower motor resister, which controls the fan speeds. Disconnect the multi-wire connector from the blower motor resister next to the blower motor. Start the car and turn the air conditioning on. Test the connector for power at the terminals in the connector using the voltmeter. If there is power, reinstall the connector to the resister.
What should the voltage be on a blower motor?
If those are OK than backprobe the blower motor connector and check for power on terminal 1. Check terminal 2 for a variable voltage, this should be 12v with the fan control knob on off and 5v or full ground on full. If that checks out replace the blower motor.
How can I tell if my blower motor has a problem?
Press and hold the OFF button and within 10 seconds press and release the Window Defogger button five times. The system enters the self-diagnostic mode and at the end of it, if there is a problem, the fault code will be displayed on the display.
What are the symptoms of a failed blower motor resistor?
Blower motor resistor problems. Problems with a blower motor resistor are common in many cars. The most common symptom of a failed blower motor resistor is when the heater fan only runs at high speed and doesn’t work at low speeds.
How do you test a blower motor resistor?
When a switch, a resistor, and a load are wired in series, the resistor “drops” some of the voltage passing through it, effectively reducing both current flow and voltage at the motor. A voltmeter connected to both ends of a resistor while current is passing through it to a load will measure the amount of voltage being “dropped” by the resistor.
This is the blower motor resister, which controls the fan speeds. Disconnect the multi-wire connector from the blower motor resister next to the blower motor. Start the car and turn the air conditioning on. Test the connector for power at the terminals in the connector using the voltmeter. If there is power, reinstall the connector to the resister.
Press and hold the OFF button and within 10 seconds press and release the Window Defogger button five times. The system enters the self-diagnostic mode and at the end of it, if there is a problem, the fault code will be displayed on the display.
If those are OK than backprobe the blower motor connector and check for power on terminal 1. Check terminal 2 for a variable voltage, this should be 12v with the fan control knob on off and 5v or full ground on full. If that checks out replace the blower motor.