When the resister of the blower motor starts to fail, the motor operates only intermittently . ... The higher current can make the jump across the resistor contacts that are going bad and get the blower motor to engage.
How do I know if my blower motor resistor is bad?
- Fan does not work at all, so no air comes out of the vents.
- Fan only works on some speeds and not others.
- Fan only works on the highest speed.
- Fan runs all the time and can't be controlled with the fan switch.
- You see smoke coming out of the vents.
How do you test a blower motor resistor?
Place one lead of the Ohmmeter on terminal 1 of the resistor . Place the other lead on terminal 2 and check against specifications. If this circuit is open, showing infinity on the Ohmmeter, the blower resistor must be replaced.
Can a bad blower motor blower resistor?
A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. The blower motor resistor is the component directly responsible for controlling the blower motor fan speed. If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed.
What causes a blower motor resistor to go out?
In most cases, a blower motor resistor fails due to corrosion or overheating . Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
Is there a fuse for the blower motor resistor?
A fuse is often located on the resistor board . The fuse only protects the low and medium blower speeds. High speed will still work if the resistor fuse is blown.
What are the signs of a bad blower motor?
- Weak Airflow from the Vents. This is usually the first indication that you may have a faulty blower motor. ...
- No Airflow at All. ...
- Unusually High Energy Bills. ...
- Strange Sounds. ...
- Overheating.
What happens when blower motor relay goes bad?
If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow . Any sort of electrical spikes or excessive current from a bad relay will blow the fuse and cut power in order to protect the system.
How do you troubleshoot a blower motor?
- AC Fan Doesn't Start. Even though you have the AC turned on, the fan does not start.
- AC Fan Doesn't Stop. ...
- Slow Rotating Blades. ...
- Outside Fan Blades Are Still. ...
- Rattling, Humming and Buzzing Noises. ...
- AC Runs Intermittently. ...
- No Cold Airflow.
How much does it cost to replace a blower motor resistor?
The average cost for a Blower Motor Resistor Replacement is between $108 and $137 but can vary from car to car.
Can I bypass my blower motor resistor?
In the highest speed state, the blower resistor is bypassed completely and the fan is connected directly to the car's battery, which allows maximum current through the motor. Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues power can be cut off to the motor.
What would cause a resistor to burn up?
When a resistor has been overloaded with voltage exceeding its power rating , the resistor will become very hot to touch, darken considerably and possibly even melt or catch on fire.
Can a blower motor resistor be repaired?
The resistor module is easy and inexpensive to replace. It's then typically installed in the ductwork, near the car blower—either under the dash or under the hood. (Refer to a service manual to locate yours.) Purchase a new resistor module at the auto parts store (usually less than $25).
How do you test a blower motor resistor with a multimeter?
Blower Motor Resistor Testing
Place one lead of the Ohmmeter on terminal 1 of the resistor . Place the other lead on terminal 2 and check against specifications. If this circuit is open, showing infinity on the Ohmmeter, the blower resistor must be replaced.
What is the purpose of a blower resistor?
The blower motor resistor is responsible for controlling the blower motor speed . In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.
