What is AC Blower Resistor?

It is common knowledge that resistors are among the most ubiquitous of all passive electrical components, and they may be found in an extensive range of circuits. There are a variety of resistor types that can be used, depending on the circumstance. One such component is the resistor that is connected to the motor of the fan blower. 

The resistor helps to keep the temperature in the room at a reasonable level with the help of both the heater and the air conditioner. In both of these configurations, the blower resistor is an essential component. In this article we will discuss a brief overview to the resistor that is utilized in blower motors. 

  • AC Blower Resistor: 

A resistor for an AC blower fan motor is an electrical part that may decrease the amount of current entering the motor. You may control the amount of air circulating through the room by increasing or decreasing the amount of resistance the fan encounters. When you adjust the fan’s speed, you’re actually altering the path that electricity takes via the blower motor’s resistor.

  • What to Look for in a Faulty Blower Motor Resistor:

Although blower motor resistors are generally reliable, they can fail suddenly like any other electrical part. A faulty resistor in a blower motor can be easily identified and fixed. If your AC blower motor resistor is harmful look for these symptoms: Disabling of HVAC fans , completely or at specific speeds, The maximum fan speed is the only one that functions. Vents are not releasing air. Fan speed that fluctuate or change randomly.  

  • Working of Blower Resistor:

The resistor in the blower motor regulates how fast the motor spins. In the past, adjusting the voltage given to the blower motor served this purpose. This resistor is now being utilized to send a variable signal to the motor. This resistor features many resistors, each with its own unique resistance. The standard resistor has a series connection that runs the length of the motor. So, this regulates how much power the fan motor receives. 

One or more resistors can be wired to each fan speed limit in the blowers resistor assembly. Therefore, the rotational speed of the motor can be regulated by adjusting the resistances. The motor’s ground circuit can be connected directly to the ground when the maximum speed has been requested, and the resistor will have completed a full circuit. Because of this, the blower motor is able to receive a high current and run at full speed.

  • Why The Blower Motor’s Resistor Fails:

The most common malfunction is when the heater fan only operates at full speed and does not respond to lower settings. A broken resistor might entirely disable an air conditioner heating fan. Overheating and corrosion are the main causes of this resistor’s failure. Overheating and premature failure of the resistor can result from the high electric current produced by the resistance that it provides toward the motor spinning. This may occur, for instance, if a fan blade becomes stuck or if the motor’s bearings wear out and it becomes difficult for the shaft to rotate freely.

If the blower control module fails or is broken, the blower motor will not stop running, even if the key is turned off. No airflow from vents, reduced or excessive fan speed, the inability to turn the fan off, a burning odor, a broken ground, faulty wiring and a malfunctioning switch, a blown circuit breaker and fuse, a failed thermal fuse, burnt connectors, etc. are all signs of a faulty resistor.

  • Methods for Checking the Resistor in a Blower Motor:  

A multi meter can be used to check the resistance of a blower motor. The resistor must first be visually inspected. Look about you for telltale signs of rust and scorching burns. If there is a sign of overheating connectors, you should replace the blower resistor, but only after you’ve correctly merged the wires. To rapidly check the resistance of a blower motor’s resistor, simply use a multi meter. 

Find the ohms-reading multi meter and attach one of the probes to the resistor’s common output terminal. Determine the resistance using probes at the input and output terminals. Two terminals’ resistance can be calculated simultaneously, but only after the common terminal and the speed-control terminal have been determined.

  • What are the Signs that a Resistor Is Faulty?

In addition to causing problems for the entire HVAC system, a faulty blower motor resistor will result in the following: the blower motor operating at a single speed, the various airflow settings being ineffective, and the vents being unable to release any air at all.

  • Use Cases

A resistor for a blower motor can be used for a variety of purposes, including:

The blower motor’s RPM can be adjusted with this resistor. In reality, this type of resistor is a solid state component that sends a varying signal to the blower motor and regulates the current flow throughout the fan. So that sums up my research into the resistor used in fan blowers. Removing the old resistor, disconnecting the wires, and replacing it with a new one are the primary processes in changing the blower motor resistor.

  • Features and Specification:

The following are some of the features and specifications of a resistor for a blower motor.

  • This application makes use of a DC series motor.
  • The resistor in the blower motor weighs about 1.5 pounds.
  • Dependable and of superior quality.
  • The blower motor can draw up to 27 kW of electricity at its peak.
  • The quality of their finish and durability are also exceptional.
  • It has four different poles.
  • Maximum RPMs are 1750.
  • A DBR fan is used to cool the surface.
  • In a vertical orientation.
  • The four brush holders are a nice touch.
  • These walls are insulated to a Class H standard.
  • The motor’s armature temperature has reached 80 degrees Celsius.
  • There is an 85 C threshold for the commutator.
  • The absolute maximum bearing temp is 90 degrees Celsius.