In this tutorial, I'll walk you through the step-by-step process for testing the radiator fan motor.
With your test results, you'll quickly figure out if the radiator fan motor is working properly or needs to be replaced.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 1.6L Honda Civic CX: 1995, 1996, 1997, 1998, 1999, 2000.
- 1.6L Honda Civic DX: 1995, 1996, 1997, 1998, 1999, 2000.
- 1.6L Honda Civic EX: 1995, 1996, 1997, 1998, 1999, 2000.
- 1.6L Honda Civic LX: 1995, 1996, 1997, 1998, 1999, 2000.
WIRING DIAGRAM: You can find the radiator fan motor wiring diagram here:
- Radiator And Condenser Fan Motor Circuit Wiring Diagram (1995 1.6L Honda Civic).
- Radiator And Condenser Fan Motor Circuit Wiring Diagram (1996-1998 1.6L Honda Civic).
- Radiator And Condenser Fan Motor Circuit Wiring Diagram (1999-2000 1.6L Honda Civic).
Radiator Fan Switch Test: The radiator fan motor gets activated by the coolant temp switch (located on the thermostat housing). This switch can easily be tested and this tutorial will help you with the test step-by-step:
These other tutorials may come in handy:
- Common Causes Of Engine Overheating (1995-2000 1.6L Honda Civic).
- How To Bench-Test The Radiator Fan Relay (1996-2000 1.6L Honda Civic).
- How To Test For A Blown Head Gasket (1995-2000 1.6L Honda Civic).
Symptoms Of A Bad Radiator Fan Motor
When the engine reaches a certain coolant temperature, the coolant temp switch (also known as the radiator fan switch) in your Honda Civic turns on the radiator fan to keep the engine cool.
Over time, the bearings in the radiator fan motor can wear out, causing the fan motor's shaft to experience more friction as it spins.
As this friction increases, the fan motor starts drawing more current to operate.
Eventually, this extra current can blow the radiator fan motor fuse or burn out the fan motor relay. When that happens, the radiator fan motor will stop working as it should.
These are some common symptoms of a bad radiator fan motor in a 1995–2000 1.6L Honda Civic:
- Engine Overheating: The engine temperature rises, especially when idling or in stop-and-go traffic, because one or both fans aren't effectively cooling the engine.
- Blown Fuse: The radiator fan motor fuse may blow repeatedly because the fan motor is drawing too much current.
- Burnt-Out Relay: A failing fan motor can burn out the radiator fan relay, preventing the fan from turning on.
- Strange Noises: Grinding or squealing sounds from the fan motor may signal worn-out bearings.
- Fan Not Turning On: The radiator fan doesn't engage when the engine gets hot.
Where To Buy The Radiator Fan Motor
The radiator fan motor on the 1997-2001 1.6L Honda Civic isn't an expensive part. The following links will help you comparison shop and save a few bucks:
TEST 1: Testing The Amperage Draw Of The Radiator Fan Motor
The first step is to find out if the radiator fan motor is drawing too much current (a clear sign it's bad) by performing an amperage draw test.
To perform this test correctly, it's important to know the amperage rating of the fuse that protects the radiator fan motor:
- Radiator fan motor fuse (1995 Civic): 15 Amps (Fuse 33, Under-Hood Fuse Box).
- Radiator fan motor fuse (1996-2000 Civic): 20 Amps (Fuse 57, Under-Hood Fuse Box).
This means the radiator fan motor cannot draw more current than the amperage rating of its fuse. If the fan motor draws more than the fuse's rating, the fuse will blow.
To test the amperage draw of the fan motor, measure the motor's resistance with a multimeter set to Ohms mode and use Ohm's Law to calculate its amperage draw: Amps = Volts ÷ Ohms.
IMPORTANT: Make sure the fan motor blades don't move while you're measuring resistance. Any movement will throw off the reading and make the results inaccurate.
Let's dive in:
- 1
Disconnect the radiator fan motor from its electrical connector.
- 2
Place your multimeter in Ohms mode.
- 3
Measure the resistance of the fan motor across pins 1 and 2 with your multimeter (see photo above).
NOTE: The test is done on the connector coming out of the fan motor. This connector has male spade terminals. - 4
Divide your resistance value by 12.5. 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 0.4 Ohms. This is what the math would look like: 12.5 ÷ 0.4 = 31.25 and this would translate to 31.25 Amps. - 5
Amperage Draw Specification:
Radiator fan motor: No greater than 15 Amps (1995 Civic) or 20 amps (1996-2000 Civic).
Let's take a look at your test results:
CASE 1: The amperage draw of the fan motor is within specification. This the correct and expected test result.
The next step is to manually apply battery power and Ground, from your Honda Civic's battery, to the fan motor itself. For this test go to: TEST 2: Applying Power And Ground To The Radiator Fan Motor.
CASE 2: The amperage draw is higher than specified for your particular Honda Civic. This result tells you that your Honda Civic's radiator fan motor is defective and needs to be replaced —even if it runs.
Here's why: When the fan motor draws more than the specified current, it's a sign that its internal components, such as the bearings or windings, are worn out. This excess current can and will blow the fan motor fuse or burn out the relay.
So, even if the fan motor runs, its high amperage draw risks further damage to the cooling system and electrical components.
TEST 2: Applying Power And Ground To The Radiator Fan Motor
Now that you've confirmed the fan motor is drawing less than the specified amperage, it's time to move on to the next test. In this step, you'll apply battery power and ground directly to the radiator fan motor on your 1.6L Honda Civic.
To do this, you'll need a set of jumper wires to connect battery power and ground to the fan motor.
IMPORTANT: Only perform this test if the fan motor's amperage draw is less than 15 to 20 Amps (as specified in TEST 1). If the amperage draw exceeds the rating of the fuse that supplies it with power, the fan motor is defective —even if it runs when battery power and ground are applied.
These are the test steps:
- 1
Disconnect the fan motor from its electrical connector.
The connector has 2 wires. The blue (BLU) wire supplies power and the black (BLK) wire supplies Ground. - 2
Apply battery power to the fan motor terminal identified with the number 2 in the illustration above.
You'll be applying power to the male spade terminal (of the radiator fan motor itself) that connects to the BLU wire of the electrical connector. - 3
Apply chassis Ground to the radiator fan motor terminal identified with the number 1 in the illustration above.
You'll be applying Ground to the male spade terminal (of the fan motor itself) that connects to the BLK wire of the electrical connector. - 4
The radiator fan motor should run.
Let's take a look at your test results:
CASE 1: The radiator fan motor ran. This is the correct test result.
You can conclude that your Honda Civic's radiator fan motor is not defective if you have:
- Confirmed that the fan motor's amperage draw is not higher than the amperage rating of its fuse (TEST 1).
- Confirmed that the fan motor runs when applying 12 Volts and Ground to it (this test section).
The fan motor is activated by the coolant temp switch located on the thermostat housing. This tutorial will help you test it:
CASE 2: The radiator fan motor DID NOT run. This test result tells you that the radiator fan motor is defective and needs to be replaced.
More 1.6L Civic Tutorials
You can find a complete list of 1.6L Honda Civic tutorials in this index:
Here's a small sample of the 1.6L Honda Civic tutorials you'll find in the index:
- Testing Shift Control Solenoid Valves A and B (1996-2000 1.6L Honda Civic).
- How To Test The Alternator (1996-2000 1.6L Honda Civic).
- How To Test: Lock-up Control Solenoid Valves (1996-2000 1.6L Honda Civic).
- How To Test Trouble Code P0135 (1995-2000 Honda 1.6L).
- How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at:easyautodiagnostics.com).
If this info saved the day, buy me a beer!
