Testing the blower motor is pretty easy on the 2.3L Ford Ranger (specially because it's in an easy to access place).
In this tutorial I'll show you the 2 tests that'll tell you if the blower motor is defective or not. The cool thing is that you don't need any expensive test equipment to perform them.
I've also included a link to the blower motor circuit diagram that'll further help you in diagnosing a blower motor problem.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Motor Del Soplador (1995-1997 2.3L Ford Ranger) (at: autotecnico-online.com).
NOTE: You can find the 1995-1997 2.3L Ford Ranger blower motor circuit diagram here: Blower Motor Circuit Diagram (1995-1997 2.3L Ford Ranger).
The following tutorial on how to test the blower resistor may also be of help: Testing The Blower Resistor (1995-1997 2.3L Ford Ranger).
Blower Motor Basics
As you're probably already aware, the blower motor has a 2 wire electrical connector. One wire is a pink with white stripe (PNK/WHT) wire and the other is an orange with black stripe (ORG/BLK) wire.
In a nutshell, the PNK/WHT wire feeds your 2.3L Ford Ranger with battery power and the ORG/BLK wire provides Ground. Now, to be bit more specific: the Ground circuit has to be routed thru' the blower resistor, then thru the blower switch, and finally thru' the vent control switch to reach its final destination.
To get a better idea of how power and Ground are routed thru' the blower motor, blower resistor, and blower switch circuits; check out the circuit diagram here: Blower Motor Circuit Diagram (1995-1997 2.3L Ford Ranger).
Now, when the blower motor fails in your Ford Ranger, you're gonna' see one of the following symptoms:
- The blower motor will stop working completely.
- The blower motor will run, but run with a lot of bearing noise.
A blower motor with worn out bearings will use an extreme amount of current (from the mechanical resistance to the motor rotation). This high amperage draw can overheat and destroy the blower motor resistor.
TEST 1: Testing The Amperage Draw Of The Blower Motor
Our first test will involve testing the amperage draw of the blower motor. We need to make sure that it's using less than 40 Amps when it runs.
To find out the blower motor's amperage draw, we're going to test the resistance of the blower motor and then using Ohm's Law, we will calculate it's amperage draw (Ohms Law: Amps=Volts ÷ Ohms).
This is a very simple and easy test that will give us a very accurate test result and will let us know if the blower motor is defective or not right off the bat.
NOTE: If you don't have a multimeter and need to buy one, check out my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing.
Let's get started:
Disconnect the blower motor from its electrical connector.
Place your multimeter in Ohms mode.
Measure the resistance of the blower motor with your multimeter. You'll be testing across the blower motor's connector and not the vehicle's wiring harness connector.
Divide 12.5 by the resistance value you got in step 3 (12.5 is the battery voltage). The result of this calculation is the amount of amperage the fan motor is using.
To be a little more specific: Let's say that the resistance reading was .4 Ohms. This is what the math would look like: 12.5 ÷ .4 = 31.25 and this would translate to 31.25 Amps.
Let's take a look at your amperage draw test result:
CASE 1: The amperage draw is under 40 Amps. This is the correct and expected test result and let's you know that the blower motor amperage draw is within specification.
The next step is to manually apply power and ground to the blower motor itself. For this test go to: TEST 2: Applying Power And Ground To The Blower Motor.
CASE 2: The amperage draw is 40 Amps or more. This test result tells you that your 2.3L Ford Ranger's blower motor is defective and needs to be replaced.
Even if the blower motor is running, it's using way to much current. This excessive current draw will blow the blower motor fuse and/or fry the blower resistor.