How To Test HVAC Blower Motor With Multimeter

The blower motor is one of the most important parts of your HVAC system, which means it’s crucial to know how to test this part to ensure it stays in good working condition. Let’s go over a few ways to test the HVAC blower motor with a multimeter.

What Is A Blower Motor?

HVAC blower motors are types of fans that are used to circulate air through a heating or cooling system. These motors come in different sizes and speeds, which can be used for both residential and commercial applications.

The squirrel cage blower is the most common type of blower motor used today. This motor has a series of fins on the outside, helping move air throughout the system. Squirrel cage blowers are typically found in air conditioners and furnaces. This motor can be controlled by thermostats, timers, and speed controls.

The inline blower is another type of blower motor. These blowers are mounted directly to the ductwork of a heating or cooling system. More intricate than squirrel blower motors, they are commonly used in larger systems.

Blower motors are undoubtedly an essential piece of any heating or cooling system. They can be used in a variety of applications in homes or businesses.

Blower Motor Types

Let’s take a look at the most common blower motor types below.

Single-Speed

Single-speed is the most common blower motor type. They feature only one speed and are usually found in lower-end furnaces.

Multi-Speed

Multi-speed motors offer two or more speeds, giving the furnace more control as it heats the home. Higher-end furnaces typically feature multi-speed motors.

Variable Speed

Offering an infinite number of speeds, variable speed motors allow for precise heating and cooling. These motors are very energy efficient and can save users money on utility bills.

Equipment And Supplies Needed For Multimeter Test

In order to test the blower motor with a multimeter, you will have to set the multimeter to the “resistance” or “ohms” setting. Next, touch the probes of the multimeter to the terminals on your blower motor. If the resistance reading is infinite, it means that there is an open circuit, making the blower motor defective.

If the resistance reading falls within a certain range (typically between 1-20 ohms), it means the motor is properly functioning. When you do not have a multimeter, you can test the motor by connecting it to a power source (like a battery) and seeing if it will turn on. The motor is deemed defective if it doesn’t turn on.

To test the motor with a multimeter, you will need the following:

• Multimeter.
• Test lead.
• Blower motor.

How To Test HVAC Blower Motor With A Multimeter

Follow these simple steps:

• Begin by setting your multimeter to the Ohms setting.
• Disconnect your blower motor lead wires from the vehicle’s electrical connector.
• Touch one lead of the multimeter to one of the blower motor’s terminals with the leads still disconnected.
• Touch the other multimeter lead to the other blower motor’s terminal.
• If the multimeter registers a reading within the normal range, it is in working order.
• Replacement may be needed when the multimeter registers a reading outside the normal range.