How To Test The Blower Motor (2001-2005 1.7L Honda Civic)

TEST 3: Testing The Blower Motor Relay (Part 1)

As you already may know, the blower motor relay is the one that connects the blower motor to battery power (when you turn on the heat, or A/C, in your Honda Civic).

For the blower motor relay to activate (and thus activate the blower motor), it needs battery power from two fuses. These two you have already verified are not blown in TEST 1.

To see if your Honda Civic's blower motor relay is bad, in this first part we're gonna' check that the relay' coil is getting both power and Ground. How? By testing the two terminal slots (of the under-hood relay box) that feed the relay this battery power and Ground with your multimeter.

In case you're wondering what the relay coil is, this is the winding inside the relay that, when activated by power and Ground, completes the circuit that connects the blower motor to battery power.

IMPORTANT: Be extremely careful not to damage the female metal terminals in the relay terminal slots by putting excessive pressure on them with your multimeter test leads. The only way to repair damaged female terminals (that have been permanently opened up) is replacing the entire fuse box with a new/used one.

Here are the test steps:

1. 1

   Remove the blower motor relay located in your Honda Civic's under-hood fuse box.
   
   You should now see the four terminal slots that the male terminals of the relay connect to (see the image above).

2. 2

   Locate relay terminal slot labeled with the #2 (in the image above). This is the terminal slot that feeds the blower motor relay's coil with battery power from the #14 fuse located in the under-dash fuse box.
   
   With your multimeter (in Volts DC mode) confirm that this slot has battery voltage. Battery power should be present with the key in the ON position (position II).

3. 3

   Locate relay terminal slot labeled with the #1. This is the terminal slot that feeds the blower motor relay's coil with chassis Ground.
   
   Probe this terminal for Ground by connecting the red multimeter test lead to the battery positive (+) terminal and the probing the slot labeled with the #1 with the black multimeter test lead.
   
   Your multimeter should register 12 Volts (battery voltage) whether the key is in the ON or OFF position.

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

CASE 1: Battery power and Ground were present at the indicated relay terminal slots. This is the correct and expected test result and tells you that your Honda Civic's blower motor relay's coil is getting both power (12 Volts) and Ground.

Your next step is the check that the relay terminal slot #3 is getting power and then bypassing the blower motor relay by jumpering relay terminal slots #3 and #4 together. For this test go to: TEST 4: Testing The Blower Motor Relay (Part 2).

CASE 2: Battery power WAS NOT present but Ground was present. This result tells you that the there's an open or a short in the circuit between fuse #14 (of the under-dash fuse box) and relay terminal slot #2.

Although it's beyond the scope of this tutorial to verify this condition, solving this issue will restore power to terminal slot #2 and solve the ‘no blower’ condition your Honda Civic is currently experiencing.

CASE 3: Battery power was present but Ground WAS NOT present. The blower motor relay will not activate the blower motor with this Ground missing.

Your next step is to resolve the problem causing this lack of Ground.

TEST 4: Testing The Blower Motor Relay (Part 2)

So far, you have checked that terminal slots #1 and #2 are doing their job and supplying Ground and power to your Honda Civic's blower motor relay's coil (TEST 3).

In this test step we're gonna' make sure that terminal slot #3 has power and then we're gonna' jumper terminal slots #3 and #4 together with a jumper wire.

Jumpering terminal slots #3 and #4 together (with a jumper wire) should make the blower motor fan run since this bypasses your Civic's blower motor relay. If the fan runs, then you can conclude that the blower motor relay is bad and needs to be replaced.

IMPORTANT: For this test to work, you need to jumper together (with a jumper wire) terminals #2 and #4 of the blower motor power transistor harness connector. Otherwise, this test won't work.

Here are the test steps:

1. 1

   Reconnect the blower motor to its electrical connector (if it's unplugged from previous testing).

2. 2

   Bypass the blower motor resistor (power transistor) by jumpering together terminals #2 and #4 of the blower motor power transistor's harness connector.
   
   You can find the step-by-steps instructions on how to bypass the power transistor here: TEST 2: Bypassing The Blower Motor Resistor.

3. 3

   Locate relay terminal slot labeled with the #3. This is the terminal slot that feeds the blower motor relay with battery power from the 40 amp fuse (fuse #12) located in the under-hood fuse box.
   
   With your multimeter (in Volts DC mode) confirm that this slot has battery voltage. Battery power should be present all the time (in other words, with both the key off or the key on).

4. 4

   Once you have confirmed that terminal slot #3 has power, then the next step is to jumper slot terminals #3 and #4 together using a jumper wire.
   
   Jumpering these two relay terminal slots together should activate the blower motor inside your Honda Civic (remember, the blower motor resistor must be bypassed for this to work).

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

CASE 1: Battery power was present at relay terminal slot #3 and the blower motor ran when you jumpered slot terminals #3 and #4 together. This is the correct and expected test result and tells you that the blower motor relay is bad and needs to be replaced.

I'll explain in more detail: So far you have:

• Verified that the all of the fuses that feed the blower motor ARE NOT blown and that the blower motor connector terminal #1 is not getting 12 Volts with the key on engine off (KOEO) (TEST 1).
• In TEST 3, you confirmed that relay terminal slots #1 and #2 are providing Ground and power.
• In this test, you completely bypassed the blower motor relay (by jumpering slots #3 and #4) and the blower motor fan ran.

Since the blower motor relay is getting power, Ground and the circuits between it and the blower motor are OK, it should be able to turn on the blower motor. Since it isn't, you can correctly conclude that the blower motor relay is bad and needs to be replaced.

If you're still in doubt and need to bench test the blower motor relay -the following tutorial will help you:

1. Blower Motor Relay Bench Test (2001-2005 1.7L Honda Civic).

CASE 2: Battery power WAS NOT present at relay terminal slot #3 and the blower motor DID NOT run when you jumpered relay terminal slot #3 and #4 together. This result tells you that there's an open or a short in the circuit between fuse #12 (of the under-hood fuse box) and relay terminal slot #3.

Although it's beyond the scope of this tutorial to test this circuit, I can tell you that you'll need to test the continuity between relay terminal slot #3 and fuse #12. Resolving the lack of battery power at relay terminal slot #3 will solve the ‘no blower’ condition affecting your Honda Civic.

CASE 3: Battery power was present at relay terminal slot #3 but the blower motor DID NOT run when you jumpered relay terminal slot #3 and #4 together. This result tells you that the there's an open or a short in the BLU/WHT (or GRN/WHT) wire between the blower motor connector and terminal slot #4 of the under-hood fuse box.

Although it's beyond the scope of this tutorial to test this circuit, I can tell you that you'll need to test the continuity between relay terminal slot #4 and terminal #1 of the blower motor power transistor connector. Resolving the open or short will solve the ‘no blower’ condition affecting your Honda Civic.

Where To Buy The Blower Motor And Save

The links below are to help you comparison shop online. I used to buy everything at my local auto parts store, till I found out just how over-priced everything is. Below are the links to the blower motor, blower motor relay, and the blower motor resistor (also known as the blower motor power transistor).

NOTE: Not sure if the above components fit your particular Honda Civic? Don't worry, they'll make sure the part fits once you get to the web site.

More 1.7L Honda Civic Tutorials

You can find a complete list of tutorials for you Honda 1.7L equipped car here: 1.7L Honda Civic Index Of Articles.

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

• Maintenance Required Light Reset (2001-05 1.7L Honda Civic).
• How To Do A Cylinder Balance Test (2001-2005 1.7L Honda).
• How To Test Trouble Code P0141 (2001-2005 Honda 1.7L).
• How To Test The TP Sensor (2001-2005 1.7L Honda Civic).
• How To Test Trouble Code P0135 (2001-2003 Honda 1.7L).