How To Test The Blower Motor Switch (Ford 4.9L, 5.0L, 5.8L)

TEST 2: Using A Jumper Wire To Bypass The Blower Switch

Bypassing the blower motor switch is a pretty easy thing to do and comes in handy to indirectly check the blower motor resistor.

All that's required is the use of a jumper wire to jumper together 2 terminals of the blower motor switch connector.

As you bypass each blower speed, the blower motor should run if everything is OK.

IMPORTANT: Use a small diameter wire as a jumper wire or you run the risk of damaging the blower motor switch connector's female metal terminals. If you use a too thick jumper wire, you may permanently open these terminals up and create an intermittent ‘open’ problem.

Alright, these are the test steps:

1. 1

   Disconnect the blower motor control switch from its harness connector and turn the key to the on position (but no need to start the engine).
   
   NOTE: All of the tests in this section are done on the blower switch's harness connector and not on the switch itself. The illustrations in the image viewer show the front view of the female metal terminals of the connector.

2. 2

   Jumper terminals 2 and 4 together. This is the circuit that controls blower speed M1.
   
   The correct test result is for the blower motor to run on M1 speed.

3. 3

   Jumper terminals 2 and 3 together. This is the circuit that controls blower speed M2.
   
   The correct test result is for the blower motor to run on M2 speed.

4. 4

   Jumper terminals 2 and 1 together. This is the circuit that controls blower speed HI.
   
   The correct test result is for the blower motor to run on HI speed.

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

CASE 1: The blower motor DID NOT run when two or all of the indicated terminals were jumpered. This tells you that that specific circuit is bad.

Although it's beyond the scope of this tutorial to test these circuits, you have eliminated the blower switch (on the A/C-Heater control panel) as bad. There's a good chance that you've got a bad blower motor resistor.

The blower resistor can be tested and the following diagnostic tutorial may be of help:

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

CASE 2: The blower motor ran when all of the indicated terminals were jumpered together. This tells you several important things:

1. That the circuits between the resistor connector and the blower motor are OK.
2. That the blower motor relay is OK.

No further testing is required of the blower resistor, the blower relay or the blower motor.

Where To Buy The Blower Switch And Save

You don't have to buy the whole A/C-Heater Control Panel to replace the blower control switch since the switch is removable. You can find the blower switch just about in anywhere. The best place to buy it and the blower switch connector (if it has melted) and save a few dollars is online.

The following links will help you comparison shop for the blower motor control switch and the connector:

More Ford 4.9L, 5.0L, 5.8L Tutorials

You can find a complete list of tutorials for 4.9L, 5.0L or 5.8L equipped Fords here: Ford 4.9L, 5.0L, 5.9L Index Of Articles.

Here's a small sample of the tutorials you'll find:

1. Manifold Absolute Pressure MAP Sensor Test (Ford 4.9L, 5.0L, 5.8L).
2. Ignition Coil Test -No Spark No Start Tests (Ford 4.9L, 5.0L, 5.8L).
3. How To Troubleshoot A No Start (Ford 4.9L, 5.0L, 5.8L).
4. Testing A Blown Head Gasket (Ford 4.9L, 5.0L, 5.8L).
5. How To Test Engine Compression (4.9L, 5.0L, 5.8L).
6. How To Test The Ford Mass Air Flow (MAF) Sensor (at: easyautodiagnostics.com).