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Heater Resistors and Regulators - Common Failure Causes

The causes, symptoms, and solutions to heater resistor regulator failure.

Dealing With Heater Resistor AC Issues?

Learn Everything You Need to Know About Heater Resistors

Are you trying to repair a car with air conditioning problems? If you’re no longer able to regulate the speed of the blower motor, the vehicle may have a failed heater resistor. In this 19-minute free webinar, you will learn the common causes of failure for this part and how to fix them.

What Are Heater Resistors and Regulators?

A blower motor is an essential component in air conditioning systems. It directs air through the AC system into the cabin. Depending on the vehicle, the blower motor is located in different locations inside the dash. A heater resistor regulates the blower motor’s speed in cars with manual air conditioning systems. This is connected to the knob, which lets you select between three or four different blow speeds from the cabin. We’ll show you a diagram of the blower motor and how it connects to the power blower motor fuse. Vehicles with automatic AC have an electronic blower motor control module/regulator, which constantly adjusts the blower motor to achieve the desired in-cabin temperature. This webinar will elaborate  the differences between heat resistors and regulator/control modules.

What Causes Failure in Heater Resistors / Regulators

Heater resistors and regulators can fail for different reasons. We’ll go over the most common causes of failure, like overheating from blocked airflow, rust due to water damage, broken seals and more. You’ll also discover why a heater resistor failure makes it impossible to select different air speeds. At the end of the webinar, you’ll understand the main faults that cause these parts to fail.

We’ve included several technical service bulletins related to blower motor issues in the downloads section of this webinar, including common vehicle problems resulting in resistor failure. The bulletins include photos to help you identify damaged parts.


How to Diagnose Failure in Heater Resistors / Regulators

Failed heater resistors can cause more problems if the damage isn't properly identified and rectified. You’ll learn how to correctly diagnose the issue to solve it at its root cause. We will tell you where to look for damage to the heater resistor, and how to test it. Sometimes heater resistors are returned to Valeo, and no fault was found with the part. After this webinar, you’ll be able to tell if you are having a problem with the heater resistor or something else. We will mention a few possible issues with similar symptoms.

Where to Find Parts and Information after Diagnosis

Once you’ve diagnosed the issue, you can find replacement parts on the Valeo Tech@ssist portal. We offer both passive heater resistors and power transistors for ventilation control electronics. We also offer parts like cabin air filters, which you will want to replace regularly to avoid damaged heater resistors. 

The Tech@ssist portal also has many other webinars.

What You Will Learn in Our Webinar

In this webinar, you will learn:

  • What is the heater resistor and how does it work
  • What are common failures for this part and how to avoid them
  • How to diagnose damage to the heater resistors

We’ll also include downloadable materials like technical service bulletins on common causes of blower motor seizure, heater resistor failure, damaged blower motors, and more.


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