How do you test a blower motor with a multimeter?
Using a multimeter set on the Ohm scale, use the positive lead and test the black wire. To check the purple wire for current, use your ignition key and turn it to the run setting, turn the heater power to full power and set the multimeter to DC power. If your meter reads “no current” the motor is no good.
Is there a way to test a blower motor resistor?
If you want to do a quick test of the blower resistor, you can check the resistance of each of the resistors with a multimeter as follows: set the tool to read ohms (a measurement of resistance) and connect one of its probes to the common output terminal of the resistor.
How do I know if my blower motor resistor is bad?
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.
How do you bypass a blower motor resistor?
Difficulty Remove the negative battery terminal. Locate the blower motor resistor on the passenger side under the dash board. Disconnect the electrical connector to the blower motor resistor. Remove the screws or bolts to the blower motor resistor and remove the resistor.
How many ohms should a blower motor have?
While you may not know exactly what the resistance of your particular motor should be, know that it should be more than zero. A resistance measurement of less than 0.5 ohms usually indicates a short circuit in the motor winding.
How do you test a 12v motor with a multimeter?
Touch the red, negative (-) wire of the voltmeter to the red, negative terminal of the battery. At the same time, touch the black, positive (+) wire of the voltmeter to the black, positive terminal of the battery. Read the voltmeter’s display. A fully-charged car battery should read 12.6 volts at room temperature.
What happens when blower motor resistor goes bad?
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 fix a blower motor resistor?
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).
What causes blower motor resistor failure?
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.
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.
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.
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 is the purpose of a blower resistor?
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.
Where is the relay for the blower motor?
The blower motor relay is generally located in the under-hood fuse box or in the under-dash fuse box. A blown fuse can mimic relay failure.