How To Test The Blower Motor Resistor (GM 2.2L)

By: Abraham Torres-Arredondo
Created: 13 February 2014
Updated: 15 February 2024
Articl Id: 558

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TEST 2: Using A Jumper Wire To Bypass The Blower Resistor

Using A Jumper Wire To Bypass The Blower Resistor. How To Test The Blower Motor Resistor (GM 2.2L)

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The purpose of this test is to bypass the blower resistor and see if the blower runs when you jumper the circuits that make LO, M1, and M2 fan speeds.

If the blower motor runs (when you bypass the resistor) then you'll know that the blower switch, the blower relay, and the blower motor are OK.

To get an accurate test result, you need to make sure that the blower motor is OK. If you haven't checked the blower motor yet, I suggest that you test if first. The following tutorial will show you how to test it: How To Test The A/C Heater Blower Motor (GM 2.2L).

IMPORTANT: Use a small diameter wire as a jumper wire or you run the risk of damaging the blower motor resistor connector's female metal terminals. If you use a too thick jumper wire, you may permanently open these terminals up and create an intermittent ‘open’ problem.

Alright, these are the test steps:

1
Unplug the blower motor resistor from its harness connector and turn the key to the on position (but don't start the engine).

NOTE: All of the tests in this section are done on the blower resistor's harness connector and not on the resistor assembly itself. The illustrations in the image viewer show the front view of the female metal terminals of the blower resistor connector.
2
Jumper terminals A and D together and turn the vent position knob to VENT. This is the circuit that controls blower speed LO (see image 1 of 4).

The DK BLU wire connects to the A terminal and the YEL wire connects to the D terminal of the connector.

With the vent knob in SLO blower fan speed, The YEL wire now has 12 Volts which the jumper wire routes to the DK BLU wire. This should cause the blower motor should run at full speed (remember, you're bypassing the resistor assembly).

3
Jumper terminals A and C together and turn the blower switch to the M1 position (the vent position knob must be in the VENT position). Terminals A and C complete the circuit that controls blower speed M1 (see image 2 of 4).

The DK BLU wire connects to the A terminal and the TAN wire connects to the C terminal of the connector.

With the vent knob in M1 blower fan speed, The TAN wire now has 12 Volts which the jumper wire routes to the DK BLU wire. This should cause the blower motor should run at full speed (remember, you're bypassing the resistor assembly).
4
Jumper terminals A and B together and turn the blower switch to the M2 position (the vent position knob must be in the VENT position). Terminals A and B complete the circuit that controls blower speed M2 (see image 3 of 4).

The DK BLU wire connects to the A terminal and the LT BLU wire connects to the B terminal of the connector.

With the vent knob in M2 blower fan speed, The LT BLU wire now has 12 Volts which the jumper wire routes to the DK BLU wire. This should cause the blower motor should run at full speed (remember, you're bypassing the resistor assembly).

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

CASE 1: The blower motor DID NOT run when two or all of the indicated terminals were jumpered. This tells you that that specific circuit is bad or that the blower switch is bad.

CASE 2: The blower motor ran when all of the indicated terminals were jumpered together. This tells you several important things:

The blower switch (on the A/C-Heater control panel) is OK.
The blower motor relay is OK.
That the circuits between the resistor connector, the blower motor switch and the blower motor are OK.
That the blower motor is OK.

No further testing is required of the blower resistor, the blower switch, the blower relay or the blower motor.