If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed. The heating and air conditioning systems may still function at one speed, however the resistor will have to be replaced in order for full functionality to be restored.
Can you bypass a blower motor resistor?
Bypassing the resistors should run the fan on high speed. High speed requires more DC current, so high speed was fed through a relay and heavier wire to prevent the wire from burning up.
What does a resistor do on a blower motor?
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.
What are the signs of a bad blower motor resistor?
What are the symptoms of a bad blower motor resistor?
- No Air. …
- High speeds only. …
- Low speed only. …
- Fan won’t turn off. …
- Blower motor works on some settings but not others. …
- Smoking vents. …
- Burning smell.
What is the difference between a blower motor and a blower motor resistor?
The motor that runs the fan in the heating and air conditioning system in a car is called a blower motor. … A blower motor resistor is a simple electric resistor. It’s used in cars where the blower motor has only 4 or 5 fixed speeds, as on the left side in this diagram. See the photo of a Ford blower motor resistor.
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. Move the lead from terminal 2 to terminal 3 and check this reading against specifications.
Can you bypass the resistor?
A wire in the left circuit is shorting the 100Ω resistor. All current will bypass the resistor and travel through the short. So typically the assumption of a short is done by redrawing the circuit. …
What happens when a resistor fails?
When a resistor breaks down, current typically flows through the burnt resistor without any resistance and thereby passes unchecked. Other components in the circuit may become damaged from the excess current flowing through.
How much does it cost to replace a blower motor resistor?
As we can see, the blower motor resistor costs between $150 and $400 and can usually be completed in about an hour to an hour and a half. These repairs are fairly simple and usually on the cheaper side for most common vehicles.
How do you know if a resistor is bad?
How to Know If Resistors Are Good or Bad
- Turn off the power running through the circuit containing the resistor you need to test. …
- Look at the color bands around the barrels of the components for the code to determine resistor values. …
- Check resistor values with the color codes. …
- Remove one end of the resistor from the circuit board to get an accurate reading.
What happens when a 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.
Why is my blower motor not working?
In a situation where the motor doesn’t work on any speed, the most likely causes are: a blown power supply fuse, a bad motor ground connection, bad motor speed control module or a failed motor. On all systems, a failed blower motor is least likely. … Start by checking the blower fuse and HVAC controller fuse.
How long does a blower motor last in a car?
For the most part, the heater blower motor on your car is supposed to last as long as the actual vehicle does. Due to the harsh conditions that this blower motor has to operate in, it will usually end up having repair issues. There are a variety of problems that the blower motor may have that will render it useless.
Can a blower motor be repaired?
Blower Motor Replacement: When Good Parts Go Bad. … There are a number of things that can go wrong with your heating system, but if the air stops blowing altogether and the same is true on cold air settings, a blower motor replacement is likely in order. The good news is that it’s a fairly straight forward repair.
Is there a fuse for the blower motor?
If the fan doesn’t work, before pointing the finger at the blower motor, check fuses for the motor to make sure they’re still good. Many vehicles have two fuses for the blower motor, one in the interior fuse block and the other under the hood. The blower motor is usually under the dashboard on the passenger side.