Skip Navigation

Electronic Multimeter relies on readers. We may earn commissions when you purchase through our links. Check Affiliate Disclosure

How to Test a Blower Motor with Multimeter

The blower motor resistor is a component of your car’s heating and air conditioning system. It works hand-in-glove with the cooling unit to distribute heated or cooled fresh outside clean into your vehicle cabin, ensuring that you stay comfortable on even longer journeys. If strange noises come from this part, it could indicate an issue, so make sure everything operates as usual by checking out all connections before reporting anything suspicious. In this article we will see in detail how to test a blower motor with multimeter.

How to Test a Blower Motor with Multimeter

You can test the blower motor resistor using a multimeter with the following steps:

● With the power supply unplugged, use your multimeter to measure both wires—the black one on this end is essential.

● Power your engine with the ignition key to measure the blower motor electrical connector for current.

● Set your multimeter to DC and turn on both heaters or coolers to check the power output.

● The blower motor resistor is faulty if your multimeter detects no current.

We will show you how to test your blower motor with a multimeter with this guide. The device must be used correctly to produce accurate results and avoid damage.

Types of blower motors

Single-speed motors

This type of motor blows air at a constant speed.

Variable-speed motors.

This motor blows air at varying speed levels.

How does a blower motor work?

The motor works in tandem with your home’s cooling and heating system; a thermostat monitors the temperature of every room.
When it’s cold outside, the thermostat sends signals to your furnace. The machine starts up and creates warm or cool air throughout our homes.
The blower keeps your house at the perfect temperature by circulating cold or hot air around it. The fan on this machine does just what its name suggests, creating a breeze that will make you feel comfortable no matter where in any room of the residence.
The fan is responsible for moving large volumes of air through your ventilation system. The thermostat talks to this blower motor and tells it when and how fast you want the cooling or heating effect, which can be either on constant mode (so everything happens at once).
The variable-speed motor is a more efficient and versatile tool. The single-speed always resorts to cold sports as it only works when signaled by the thermostat, but you can choose between low or high speeds for different jobs with this type of blower.

How to know your blower motor needs testing?

If you are experiencing any of these problems with your HVAC system, it can only mean one thing- that the blower motor is faulty and may need testing. Some symptoms include:
1) Lacking or blowing cold air
2). Heating up only when turned on
3). Frequent cycling
4 ) weird noises coming from vents
5 ). Thunderous sound while running

Inspecting Blower Motor Using a Multimeter 

Step 1: Test The Negative Wire Using the Multimeter’s Positive Lead

You need to ensure your power supply’s cables are correctly disconnected to start the process off. The black wire typically goes towards what would be considered “negative” on a multimeter. Still, since we’ll want this one for testing instead of going directly into our instrument’s socket here, I will use my positive lead instead–and yes: It should still read ”+.

Step 2: Turn On Your Engine

Power on the engine, and use the ignition key to measure the blower motor electrical connector (purple wire) for current.

Step 3: Set Your Multimeter to DC Power and Measure

To test your heater or air conditioner, you need to turn on the power and check for current. If there isn’t any reading from the multimeter (or value), it could mean that something’s wrong with either device; so far as testing blower motors go – don’t forget about them.

Step 4: Inspect If the Relay is Not Grounded

Next, find the fuse panel access cover beside your passenger’s side shifter.
This will show you how much space there is in front of it and give an idea about what kind or size item might need room to operate.
Inspect the relay if it is grounded or not using your multimeter (Ohm scale). Then, examine without grounding the current pin to the DC range on the same device.

If you don’t see any current, look underneath the hood for your IGN fuse and unscrew its cover panel. Connect one end of a multimeter to the negative side of the battery; connect the other end to the positive terminal next To Computer Positive(+). If it’s burnt out, then I suggest replacing that too.

Step 5: Test the Connector

Make sure your car’s ignition is turned on and that you have a multimeter set up with DC scale settings to examine the connector when it comes time for repairs. If everything works as expected, then replace this relay.


If your blower motor is not working correctly, this article will help. We discuss how to test a fan using an electronic multimeter to fix the problem and quickly get it back up and running.

Frequently Asked Questions

How can you determine whether your blower motor needs to be tested?

If you’re experiencing problems with your HVAC system, it’s likely that the blower motor has gone out and needs to be replaced. Some signs of this occurring include:
1) Lacking or blowing cold air
2). Heating up only when turned on
3). Frequent cycling
4 ) weird noises coming from vents
5 ). Thunderous sound while running

Syed Muhammad Jawad

System Analyst / Founder / CEO

Explore comprehensive, expert reviews of electronic multimeters by Syed Muhammad Jawad, the respected author and electronics enthusiast. Delve into his insightful analysis, detailed comparisons, and trusted recommendations to make informed decisions on your next multimeter purchase.