How to Test the Blower Motor Resistor (GM 2.2L)

In this tutorial, I'm gonna' show you two different ways to test the blower motor resistor on your 2.2L GM vehicle.

The first test, and probably the most popular way to test the blower motor resistor is by checking the continuity of the resistors that make up the resistor assembly.

The other is by bypassing the blower resistor with a jumper wire and thus indirectly testing the blower resistor assembly.

NOTE: Even though this tutorial is filed in the GM 2.2L index of this website... and this tutorial is focused to a few vehicles... the basic testing method applies to any non-solid state resistor assembly.

To aid you in further knowing if this tutorial applies to your specific vehicle, the testing procedures apply to the following blower motor resistor numbers:

  1. Airtex/Wells 3A1017.
  2. AC Delco 1580839.
  3. Duralast DR786.
  4. Everco 20072.
  5. Four Seasons 20072.
  6. Standard Motor Products RU55.

Here are the contents of this tutorial at a quick glance:

  1. Basics of Troubleshooting the Blower Control Resistor.
  2. TEST 1: Checking Continuity of the Blower Resistor.
  3. TEST 2: Using a Jumper Wire to Bypass the Blower Resistor.
  4. Where to Buy the Blower Resistor and Save.
  5. Related Test Articles.

The following tutorial on testing the blower switch may come in handy:

  1. How to Test the A/C-Heater Blower Motor (GM 2.2L).

Basics of Troubleshooting the Blower Control Resistor

How to Test the Blower Motor Resistor (GM 2.2L)

Three different resistors make up the blower motor resistor assembly on your 2.2L equipped GM car.

As you're probably already aware, these resistors are located between the A/C-Heater control panel and the blower motor.

The purpose of these resistors is to reduce the amount of the blower motor's current that's passing through them.

As you select a blower speed, the blower motor switch reroutes battery power to a specific combination of one, two or all three of these resistors (within the blower motor resistor assembly).

It's this reduction in current (that the combination of resistor provokes) that makes the blower motor turn slower than full speed (HI).

The one blower motor speed that doesn't depend on the blower motor resistor assembly is HI... since the blower motor switch accomplishes this speed by completely bypassing the blower motor resistor assembly.

In the majority of the cases, when the blower motor resistor fails, you can visually inspect it and see that one of the resistors (which are shaped as coils) are physically burned ‘open’... but not always.

The cool thing is that you can check the integrity of each resistor and the state of the thermal fuse with a multimeter and that's how I'll show you how to test it in this tutorial.

Blower Resistor Circuit Descriptions
Pin Wire Color Description
A DK BLU Current Output to Blower Relay.
B LT BLU M2 Speed Input From Blower Switch.
C TAN M1 Speed Input From Blower Switch.
D YEL LO Speed Input From Blower Switch and Vent Selection Switch.

NOTE: There's a good chance that the color of the wires described above DOES NOT match what's on your particular vehicle. This is no cause for concern since the circuit descriptions are the same for all of the Ford vehicles covered by this repair tutorial.

TEST 1: Checking Continuity of the Blower Resistor

How to Test the Blower Motor Resistor (GM 2.2L) How to Test the Blower Motor Resistor (GM 2.2L) How to Test the Blower Motor Resistor (GM 2.2L) How to Test the Blower Motor Resistor (GM 2.2L)

Before you start this test, you should remove the blower motor resistor and check to see if all of the resistors are intact.

If any are burned ‘open’, then you've found the blower motor problem and there's no need to proceed with the continuity tests in this section. Replacing the blower resistor should solve the problem.

If the resistor looks OK, there's still a good chance the resistor assembly is bad and the best way to test them is by doing few simple continuity tests with your multimeter in Ohms mode ().

Don't worry, they're pretty easy to do and in the test steps below, I'll explain it all in the test steps below.

NOTE: All of the continuity tests are done on the blower resistor assembly itself. For the pin id, see image 4 of 4 in the image viewer).

OK, these are the test steps:

  1. 1

    Disconnect the blower motor resistor from its electrical connector and remove it from its location. Set your multimeter to Ohms mode ().

    Don't have a multimeter or need to upgrade yours? Check out my recommendation: Abe's Multimeter Recommendation (found at: easyautodiagnostics.com).

  2. 2

    Probe terminals D and A with your multimeter leads (see image 1 of 4 in the image viewer).

    Your multimeter should register continuity. Your multimeter should NOT register OL (open loop).

  3. 3

    Probe terminals C and A with your multimeter leads (see image 2 of 4 in the image viewer).

    Your multimeter should register continuity. Your multimeter should NOT register OL (open loop).

  4. 4

    Probe terminals B and A with your multimeter leads (see image 3 of 4 in the image viewer).

    Your multimeter should register continuity. Your multimeter should NOT register OL (open loop).

Let's take a look at what your test results mean:

CASE 1: One or more of the resistors you tested DID NOT have continuity (multimeter registered OL). Repeat the tests just to make sure of your test results.

If continuity is not present where indicated in the test steps above then this confirms that the blower motor resistor is bad and needs to be replaced.

If you need to replace the blower motor resistor, take a look at the section: Where to Buy the Blower Resistor and Save.

CASE 2: All circuits tested had continuity where indicated in the test steps. This is good and is the correct and expected test result that tells you that the blower motor resistor is OK and not the cause of the blower motor speed problem.

If your Cavalier's (or Beretta's, or Corsica's) blower motor resistor passed this continuity test, you can stop here. But, if you're having a blower motor fan speed issue... I would suggest the next test. The next test indirectly tests the blower switch and blower motor relay. For this test go to: TEST 2: Using a Jumper Wire to Bypass the Blower Resistor.