Testing the blower motor on the 2001-2003 Dodge Dakota and Durango, to find out if it's bad (or not), isn't hard.
I'll explain the two tests that'll help you find out if it's defective or not.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Motor Del Soplador (2001-2003 Dodge Dakota And Durango) (at: autotecnico-online.com).
NOTE: If you need to test the blower motor resistor block, see this tutorial: How To Test The Blower Motor Resistor (2001-2004 Dakota, Durango).
Blower Motor Basics
You'll notice that the blower motor is a simple 2 wire component. In a nutshell, one wire feeds it power and the other feeds it Ground.
Sooner or later, the blower motor will fail and when it does it'll do one of 2 things:
- Stop working completely.
- Run, but run with a lot of noise.
The ‘a lot noise’ I'm talking about is the growling noise that's caused by worn out blower motor bearings.
Thankfully, it can be tested easily to find out if it's defective or not.
TEST 1: Testing The Amperage Draw Of The Blower Motor
The first thing we're gonna' do is to test the blower motor's amperage draw.
We need to see if the blower motor is drawing a high amount of current (above 40 Amps) because if it is, then it's defective.
This test is important because the blower motor could run when we apply battery power and ground in the next test, but could be blowing out the blower motor fuse, or burning out the blower resistor and/or blower switch (due to a high current draw).
To find out the amperage draw, we'll test the blower motor's resistance. Then we'll divide the resistance value by 12.5 to calculate it's amperage draw (Ohms Law: Amps = Volts ÷ Ohms).
The amperage draw, of your Dakota or Durango's blower motor should be under 40 amps.
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 value). 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: Your test result resulted in a calculation of 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: Your test result resulted in a calculation of 40 Amps or more. This test result tells you that the blower motor, on your 1997-1999 Dodge Dakota, is defective and needs to be replaced.