How To Test The Blower Motor (GM 3.1L, 3.4L)

Sooner or later your 3.1L GM vehicle's blower motor is gonna'go bad and will need to be replaced.

If you've never troubleshooted one, then you've come to the right place since this tutorial will show you how to test it in a step-by-step way.

NOTE: This tutorial covers the vehicles in the box titled ‘Applies To:’ on the right column. But, the test procedure (described here) applies to any type of blower motor that has one terminal in its connector.

TEST 1: Applying Power To The Blower Motor

Depending on the exact location of the blower motor, you can test it on the car or you may have to remove it for ease of access.

My test steps below assume that you'll be testing the blower motor while it's still bolted in place on the car.

If you do remove it, you'll need to Ground the blower motor case with a battery jump start cable to complete the test.

As a safety precaution you should use a fused jumper wire or a power probe to apply battery power to the blower motor. You can make your own fused jumper wire by using an inline fuse holder that you can buy at your local auto parts store and insert a 30 amp fuse into it.

NOTE: If you remove the blower motor from its location to bench test it, you'll have to Ground the blower motor's metal case or the test won't work. Grounding the case is important due to the fact that the blower motor gets Ground through it case.

Alright, these are the test steps:

1. 1

   Disconnect the blower control motor from its 1-wire electrical connector.
   
   You'll notice that this wire will be a purple (PPL) color.

2. 2

   Connect a fused jumper wire to the blower motor male spade terminal that connects to the PPL wire of the connector.
   
   The blower motor should run as you soon as you connect the other end of this fused jumper to your vehicle's car battery positive terminal.
   
   NOTE: If you're testing the blower motor while it's still bolted in place, you don't have to Ground it with a separate Ground jumper wire.

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

CASE 1: The blower motor ran when you applied battery power with the jumper wire. This is the correct and expected test result and tells you that the blower motor is good.

If you're having issues with the blower motor not working, it's possible that the blower resistor is bad and needs to be tested. Although it's beyond the scope of this tutorial to test the blower resistor, you have at least eliminated the blower motor as bad.

CASE 2: The blower motor DID NOT run when you applied battery power with the jumper wire. This test result tells you that the blower motor is bad and needs to be replaced.

The next subheading will show you where you can buy the blower motor and save a few bucks.

Where To Buy The Blower Motor And Save

There's a good chance that you can buy the original AC Delco blower motor online for a whole lot cheaper than somewhere local.

The following links will help you comparison shop for the blower motor:

More Test Articles

I've written quite a few 3.1L/3.4L GM 'how to test' tutorials that may help you troubleshoot the issues on your car or mini-van. You can find them here: GM 3.1L, 3.4L Index Of Articles.

Here's a small sample of the articles/tutorials you'll find in the index:

• Coolant Leaking From Intake Gaskets (GM 3.1L, 3.4L).
• How To Do A Blown Head Gasket Test (GM 3.1L, 3.4L).
• How To Test Engine Compression (GM 3.1L, 3.4L).
• How To Test The GM EGR Valve (Buick, Chevy, Olds, Pontiac) (at: easyautodiagnostics.com).
• How To Test The GM MAF Sensor (GM 3.1L, 3.4L, 4.3L, 5.0L and 5.7L) (at: easyautodiagnostics.com).