How To Test The Blower Control Switch With A Multimeter (Ford 4.9L, 5.0L, 5.8L)

Testing your Ford vehicle's blower motor switch to see if it's fried (or not), can be done with a set of simple multimeter continuity tests.

In this tutorial, I'll show you how to get it done in a step-by-step way.

NOTE: Even though this tutorial is filed in the Ford 4.9L, 5.0L, 5.8L index of this website... this tutorial applies to quite a few Ford vehicles. This is because this particular blower motor switch was used in several models from 1992 to 2006. To find out if your particular Ford vehicle is covered by this troubleshooting tutorial, check the box titled “Applies To:” on the right column.

To aid you in further knowing if this tutorial applies to your Ford car, mini-van, pickup or SUV... if your vehicle uses one of the following blower motor switch numbers, this tutorial applies to your vehicle:

  1. Airtex/Wells 1S1067.
  2. Duralast SW1067.
  3. Everco 20044.
  4. Four Seasons 20044.
  5. Motorcraft YH588.
  6. Santech MT1306.
  7. Standard Motor Products: HS229 and HS229T.

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

  1. Basics Of Troubleshooting The Blower Control Switch.
  2. TEST 1: Checking The Continuity Of The Blower Switch Fan Speeds.
  3. TEST 2: Using A Jumper Wire To Bypass The Blower Resistor.
  4. Where To Buy The Blower Switch And Save.
  5. More Ford 4.9L, 5.0L, 5.8L Tutorials.

En Español You can find this tutorial in Spanish here: Cómo Probar el Interruptor del Motor Soplador (4.9L, 5.0L, 5.8L Ford) (at: autotecnico-online.com).

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

  1. How To Test The Blower Motor Resistor (Ford 4.9L, 5.0L, 5.8L).

Basics Of Troubleshooting The Blower Control Switch

How To Test The Blower Control Switch With A Multimeter (Ford 4.9L, 5.0L, 5.8L)

In a nutshell, the blower motor switch's job is to reroute the current coming from the blower motor and that's seeking a path to ground to one of several resistors inside the blower resistor assembly.

The blower switch does this mechanically by opening (interrupting) and closing (connecting) the two contacts necessary to divert the incoming blower motor current.

To really explain this and make it make more sense, let me give you an example of what happens when you turn the blower fan speed knob from OFF to LO:

  1. When the blower fan is in the LO position:
    1. Battery power is available on terminal 2 of the blower switch connector.
    2. Inside the blower motor switch this battery power goes nowhere.
  2. When you turn the blower fan switch to the M1 position:
    1. Battery power is available on terminal 2 of the blower switch connector.
    2. This battery power is now diverted to terminal 4 of the blower switch harness connector.
    3. In tech speak: circuit 2 and 4 is now considered ‘closed’.
    4. The blower motor now runs in M1 speed.
  3. This interruption and diverting of battery power goes on for all of the other blower fan speeds.

Since these are mechanical connections the blower switch is making to open and close these circuits... over time and use these contacts become pitted and covered in carbon (from the electrical arching that occurs when the contacts close). When this happens, one or several of the blower fan speeds stop working.

The cool thing is that diagnosing/troubleshooting the blower switch isn't hard. The following circuit descriptions will help:

Blower Switch Circuit Descriptions
Pin Wire Color Description
1 BLK Chassis Ground.
2 ORG/BLK Input From Blower Motor.
3 YEL M2 Speed Output.
4 DK GRN M1 Speed Output.

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 Switch Fan Speeds

How To Test The Blower Control Switch With A Multimeter (Ford 4.9L, 5.0L, 5.8L)

Testing to see if your Ford's blower motor switch is bad (or not) can be done with a simple multimeter resistance test.

These resistance tests are also known as continuity tests and are done with your multimeter in Ohms mode ().

Don't worry, they're pretty easy to do and in the test steps below, I'll explain what two circuits should have continuity depending on what speed the blower switch knob is in (the hard part is removing the A/C-Heater control panel to access the rear of the blower control switch).

IMPORTANT: All multimeter continuity tests described in this test section are done on the blower switch's male spade metal terminals and not on the switch's connector. All the illustrations (in the image viewer) are of the blower switch itself and NOT of the connector (see image 4 of 4).

OK, these are the test steps:

  1. 1

    Remove the A/C-Heater control panel from the dash and unplug the blower motor switch from its harness connector. 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

    With the blower switch knob set to the M1 position.

    You should have continuity between 2 and 4 (see the illustration above to identify the proper male spade terminals to probe).

  3. 3

    With the blower switch knob set to the M2 position.

    You should have continuity between 2 and 3.

  4. 4

    With the blower switch knob set to the HI position.

    You should have continuity between 2 and 1.

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


CASE 1: One or more of the circuits tested DID NOT have continuity when the blower fan speed knob was turned. Repeat the tests just to make sure of your test results.

If continuity is not present where indicated in the test steps above and this lack of continuity coincides with the blower fan speed that's not working on your Ford pickup or SUV... then you've found the cause of the problem.

Replace the blower switch in the A/C-Heater control panel with a new one to solve the problem. To comparison shop for the blower control switch, take a look at this section here: Where To Buy The Blower Switch 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 fan switch (in the A/C-Heater control panel) is OK.

Your next step is to bypass the blower resistor using a simple jumper wire. For this test go to: TEST 2: Using A Jumper Wire To Bypass The Blower Switch.