How To Test The Blower Motor Resistor (1995-2003 Chevy S10 And GMC Sonoma)

The 1995-2003 Chevy S10 (GMC Sonoma) blower motor resistor can be tested easily and in this tutorial I'll explain how to do it in a step-by-step way.

NOTE: This tutorial applies to the 1995-2003 Chevy S10 and GMC Sonoma equipped with a 2.2L or a 4.3L V6, since the same blower motor resistor block is used in them all.

Contents of this tutorial at a glance:

  1. Blower Motor Resistor Basics.
  2. TEST 1: Resistance Testing The Blower Motor Resistor.
  3. Blower Resistor Continuity Specification Tables.
  4. Where To Buy The Blower Motor Resistor.
  5. More 2.2L GM Tutorials.

NOTE: You can find the blower motor test here: Blower Motor Test (1994-2003 2.2L Chevy S10, GMC Sonoma).

Blower Motor Resistor Basics

The blower motor resistor block is located right next to the blower motor (in the engine compartment) and is very accessible.

When the blower motor resistor block fails, you'll usually see one of the following symptoms:

  1. Blower motor works in high-speed only.
  2. Blower motor works in some speeds, but NOT all speeds.

What usually happens, when the blower motor resistor block fails, one of the coils has burned out.

When this happens, it's not unusual to see that the resistor block's connector has melted too.

TEST 1: Resistance Testing The Blower Motor Resistor

Resistance Testing The Blower Motor Resistor. How To Test The Blower Motor Resistor (1995-2003 Chevy S10 And GMC Sonoma) Blower Motor Resistor Pin Out. How To Test The Blower Motor Resistor (1995-2003 Chevy S10 And GMC Sonoma)

To get our resistor block diagnostic on the way, we're gonna' do a simple multimeter continuity test with the multimeter in Ohms mode.

If the resistor block is defective, you'll get a no-continuity test result when testing across the indicated terminals. This means that your multimeter will read OL if there's no continuity.

If the resistor block is OK, then you'll get a continuity reading across the indicated terminals in the test instructions below.

To see the specific readings I got from a good Chevy S10 resistor block, see this section: Blower Resistor Continuity Specification Tables.

OK, let's get started:

  1. 1

    Disconnect the blower motor resistor from its connector and remove it from its location.

  2. 2

    Visually inspect the blower motor resistor block and connector for burn damage and severe corrosion.

  3. 3

    Place your multimeter in Ohms mode.

  4. 4

    Check for continuity across two terminals at a time. Continuity should be present between all terminals.

    NOTE: If continuity DOES NOT exist between 2 terminals, your multimeter will display the letters OL (Open Loop).

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

CASE 1: Continuity exists between all the blower motor resistor terminals. This is the correct and expected test result.

If there isn't any burn damage to the resistor's coils or its connector, then you can conclude the blower motor resistor block is OK and not defective.

CASE 2: Continuity DOES NOT exist between some of the blower motor resistor terminals. This test result tells you that the blower motor resistor is defective and needs to be replaced.

If the resistor block's connector is damaged or is melted, it must be replaced with a new one.