How To Test The Blower Motor Switch (1998-2000 3.0L Ford Ranger)

This tutorial will help you to test the blower motor switch on the 1998, 1999, and 2000 3.0L Ford Ranger and Mazda B3000.

You'll be able to test the low (L)O, medium 1 (M1), and high (M2), and high (HI) blower motor speeds.

By the way, you don't have to remove the blower switch from the AC/Heater control panel to test it.

You can find this tutorial in Spanish here: Cómo Probar El Interruptor De Velocidades Del Soplador (1998-2000 3.0L Ford Ranger) (at: autotecnico-online.com).

The following tutorial will help you test the blower motor:

• How To Test The Blower Motor (1998-2000 3.0L Ford Ranger).

NOTE: You can find the blower motor circuit diagram here: Blower Motor Circuit Diagram (1998-2000 3.0L Ford Ranger).

Symptoms Of A Defective Blower Motor Switch

The blower switch has selections for 4 blower speeds. These speeds are: low (LO), medium one (M1), medium two (M2), and high (HI).

When the blower motor fails on your 3.0L Ford Ranger or Mazda B3000 one or several of the blower speeds will stop working.

CIRCUIT DIAGRAM: To get a better idea of these different circuits, take a look at the blower motor circuit diagram here: Blower Motor Circuit Diagram (1998-2000 3.0L Ford Ranger).

Check The Blower Motor Circuit Fuses First

There are two fuses that supply power to the blower motor circuit and it's a good idea to make sure that they're not blown (before we jump into the tests).

These are the fuses you need to check:

Fuse #2 of the dash fuse box. This is a 7.5 Amps fuse. Visually inspect that it is not blown.

BLOWER MOTOR fuse of the under hood fuse box. This is a 40 Amp fuse. Check that it is not blown.

If any of these fuses are blown, replace them and see if this solves the problem. If not blown, continue to TEST 1.

TEST 1: Testing The LO Blower Speed Circuit

As you're already aware, the blower switch is part of the AC/Heater control panel. The cool thing is that you don't have to remove it to test it. We're gonna' be performing all of our tests, not on the switch itself but on the blower motor resistor connector.

We'll start off by testing the low (LO) blower speed. If you've taken a look at the blower motor wiring diagram, you'll notice that the low (LO) speed circuit bypasses the blower switch entirely.

The actual component, on the AC/Heater control panel, that makes the LO blower motor speed happen is the vent selection control switch.

As a matter of fact, for the LO, M1, M2, and HI speeds to work the vent selection control switch has to be in any position but OFF.

To find out if the vent selection control switch is defective or not, we're gonna' use a 12 Volt automotive test light on the blower resistor connector (the photo above is of the blower resistor electrical connector).

CIRCUIT DIAGRAM: Blower Motor Circuit Diagram (1998-2000 3.0L Ford Ranger).

These are the test steps:

1. 1

   Disconnect the blower resistor and the blower motor from their electrical connectors.
   
   NOTE: This and all the other tests are done with the ignition key in its OFF position.

2. 2

   Place the AC/Heater Control Panel's vent selection control knob on any selection but OFF.
   
   You can find the descriptions of the vent selections (of the vent control knob) here: Identifying The Vent Control Switch Selections.

3. 3

   Connect the 12 Volt test light's alligator clip to the positive (+) battery terminal of your Ford Ranger's battery.

4. 4

   Select blower motor speed LO on the AC/Heater Control Panel.

5. 5

   Probe the female terminal identified with the #2, of the resistor block's connector, with the metallic point of your 12 Volt test light (see photo above).
   
   Female terminal #2 has a red with orange stripe (RED/ORG) wire connecting to it.

6. 6

   The 12 Volt test light should come on if the LO circuit is OK.

Let's examine your test result:

CASE 1: The 12 Volt test light turned on. This is the correct test result and lets you know that the AC/Heater Control Panel's vent control switch is working correctly.

Now that we've made sure that the vent control switch is working, we can test the other 3 speeds. The next test is to check that the M1 speed circuit inside the blower motor switch is functioning correctly. For this test go to: TEST 2: Testing The M1 Blower Speed Circuit.

CASE 2: The 12 Volt test light DID NOT turn on. This test result lets you know that the AC/Heater Control Panel's vent control switch is defective. Replace the vent control switch.