How to test blower fan motor resistance?

AIP shares with you the" How to test blower fan motor resistance?".

September 15, 2023

How to test blower fan motor resistance?

Air conditioning is a very important device in homes and vehicles. Whether it is summer or winter, these devices need to perform at their best so that we can stay as comfortable as ever. However, just like other electronic devices, these devices can fail, and these failures are related to the blower motor. The blower resistance plays an important role in the motor, so it is important to understand how to test the blower motor resistance to ensure that it is in good working order. important.

Ⅰ.What is a blower?

Blower fan motor

A blower is a powerful motor that provides ventilation or air circulation to equipment or buildings that require airflow. A blower motor is a type of fan. This type of fan mainly consists of three components: ① fan - air moves through its blades; ② powerful motor with lubricated moving parts - used to rotate the fan blades; ③ power supply that provides power to the motor —Metal or plastic housing containing assembled parts. For automatic cooling systems, a thermostat monitors the room temperature and when a trigger temperature level is reached, a signal is sent to the furnace within the system, and it is this furnace that generates the hot and cold air.

Ⅱ.Blower motor type:

Blower motors we often see in our daily lives:

Blower motor

■Single speed: The most common type of blower motor, these motors only have one speed and are typically used on low-end units.

■Multi-speed: Based on single-speed motors, multi-speed motors offer two or more speeds, which allow the furnace to control heating better. These motors are often used in high-end furnaces.

■Variable speed: The best type of blower motor on the market, variable speed motors offer an unlimited number of speeds, allowing for very precise heating and cooling. Variable-speed motors are very energy efficient and can save you money on utility bills.

Ⅲ.How to know if the blower is broken

Common symptoms of blower motor damage:

■Reduced airspeed

■The airspeed is weak, and

■Complete lack of air in ventilation areas

It's easier to notice reduced airflow from the vents when using a single-speed blower; you'll notice weaker airflow from the variable-speed blower when using a variable-speed blower; the easiest symptom to recognize is when you're not getting any airflow from your HVAC or cooling at all. when the system receives any air.

Ⅳ.What causes the blower motor to break?

There are several key factors that can cause a blower motor to go bad.

①Long -term wear and tear. Over time, components in your motor can malfunction or become damaged, causing it to no longer function properly.

②Dirt and debris accumulate on the motor, which will cause the fan motor to work less efficiently and eventually fail.

③ Improper maintenance. If the motor is not cleaned and lubricated regularly, it will eventually start to cause problems. If the wrong oil or grease is used on a motor, it can damage the components and cause them to fail.

④If the motor is not used correctly, the motor will be damaged in advance. For example, if a blower motor is too small, it will have to work harder and eventually burn out if you try to heat or cool a large space.

If you think your blower motor may be broken you should have it checked by a professional as soon as possible. Depending on the problem, repair or replace.

Ⅴ.What is the function of the blower motor resistance?


The speed of the blower in the vehicle can be adjusted by adjusting the resistance of the blower motor connected to the fan switch. The air conditioner can adjust the fan speed mechanically, using a rotating lever to change the resistance of the blower resistor.

The blower motor resistance determines how fast the fan spins. While this used to be accomplished by regulating the power supplied to the fan motor, most applications today use solid-state modules rather than traditional resistors to control the speed of the blower motor.

Ⅵ.Blower motor resistance position

The blower electrode resistor is located below the blower motor. Some vehicles may require the removal of the glove box to access the blower motor resistor.

Ⅶ.How to test blower motor resistance with a blower motor tester?

■ First, set the upper and lower limit parameters according to each item of the blower motor under test (AIP comprehensive tester can test resistance, withstand voltage, insulation, turns, inductance, and other items with one click)

■ Next, place the blower motor on the test bench and wire the

■ Then, start the test (starting method button or sliding cover)

■ Finally: If the resistance parameter is within the normal range, it indicates that the blower motor may be working normally; if it is outside the normal range, it indicates that the blower motor is faulty and needs to be replaced.


The blower motor resistor plays a vital role as it determines the rotation speed of the blower motor fan . The blower motor resistor is the most susceptible part of the equipment to damage. Therefore, when the resistor in the blower motor fails, it should be replaced immediately.

AIP focuses on global motor testing and provides one-stop motor testing solutions. It currently has mature blower fan motor testing solutions. For more blower motor tester and other motor testing equipment problems, you can contact us through Tel/Whatsapp: +86- 13969776659, E-mail: Contact us, and we can provide you with customized blower motor testing solutions for free