Typically it’s done by measuring the voltage at the blower motor connector when it’s turned on. If there is a voltage at the motor (at least 4-6 Volt at low speed and 12 Volt at high speed), but the motor doesn’t run, the motor is bad or jammed.
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.
How many volts does the blower motor need to run?
The motors operate on 115 volts if installed on furnaces and 230 volts if installed on air handlers. voltage to motor. The line voltage must be present for the motor to operate.
How do you check blower motor voltage?
Keeping the black lead on a good ground, usually a bolt on the engine block, and the blower switch turned on, use the red lead to probe the plug that usually attaches to the blower motor. The meter should read between 9 and 11 volts or the test light will light up.
How do you diagnose a bad blower motor?
Bad Blower Motor Symptoms in HVAC
- Airflow is weak from the vents. This is often one of the first signs or symptoms of a bad blower motor. …
- Sounds Coming From the Blower. …
- Overheating is One of the Symptoms of a Bad Blower Motor in HVAC.
How much resistance should a blower motor have?
According to the service manual, it must be around 4-5 ohms. In our case the ohmmeter shows open circuit, which means the resistor has failed. Sometimes, a blower motor resistor might fail due to problems with the blower motor itself.
What are the signs of a bad blower motor resistor?
Usually a bad or failing blower motor resistor will produce a few symptoms that can alert the driver of a potential issue.
- Blower motor stuck on one speed. …
- Blower motor does not work on certain settings. …
- No air from the vehicle’s vents.
How do I know if my blower motor is good?
How to Test a Blower Motor
- Use voltmeter or ohmmeter to check for a blown fuse. If you find one, replace it.
- Start car and see if blower motor works. …
- If the circuits are in good repair but the blower motor keeps blowing fuses, replace the blower motor [source: You Fix Cars].
How many amps should a blower motor draw?
Up to 20 Amps or more. Amperage is how much power a device is consuming. The Amps will be labeled on the motor’s name tag.
Why does my blower motor work sometimes?
When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds so the fan runs slower.
How do you know if your electric motor is bad?
How To Check If an Electric Motor Is Going Bad
- Check the Bearings and Shaft. A motor’s bearings are one of the most common components to go bad. …
- Inspect the Motor Windings With a Multimeter. …
- Test the Power With a Multimeter. …
- Ensure the Fan Is in Good Shape and Secure.
How do you know if a capacitor is bad on a motor?
If your electrical meter displays a microfarad value that is too high or too low, this is a sign that your capacitor is bad. Before testing your capacitor, be sure to short across the terminals with an insulated handle screwdriver. This will help you remove any stored power.
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.