A few days ago, the blower stopped working on my Civic 2001. I checked the fuses, the resistor and the relay and they all seem OK. When I bypassed the resistor, the motor turned on. Not knowing what the issue was, I reconnected all parts and to my surprise, everything worked fine... for a few minutes. I can hear a clicking noise when I turn on the fan, but the motor won't start. Any idea what the issue could be? Thanks a lot!!

 

Tap on the fan motor with a solid object(small ball peen for example) not hard ,just a few raps and see if the motor starts spinning. If it does you need a new motor....

 

If you run power and ground wires directly from the battery to the blower motor, does it run consistently at full power?

 

Thanks for the responses.

Here is where I am now: I checked the voltage at the motor and it looks normal (12 V). When I tested the ground line to the blower motor, I got a reading of 3.6 kOhms. I connected the ground to the battery, and it made the motor run at fool power.

I checked the resistor and everything looked fine. ( https://troubleshootmyvehicle.com/ho...esistor-test-1 ). I also replaced the resistor and it did not fix the issue.

I tested the voltage coming from the switch to the resistor and I got values between 3 and 10 mV which makes me think that the switch is working correctly.

It seems that connecting the ground directly to the motor causes the motor to start. When I connect it back to the resistor, it keeps working for a few mns, until it stops again. Do I have a bad motor?

Thanks in advance!!

 

Check the power transistor, which is on the ground circuit.

 

I thought the transistor and the resistor were the same things. I have tested it and replaced it, and it didn't solve the problem.

 

The "power transistor" is a single unit containing a separate resistor and transistor. See circuit diagram.

Test the Blk ground wire running to G502/G501 and the Blu/Blk, Blu/Red, and Blu/Yel wires for an open.

Your test shows that the motor is fine.

 

OK thanks, but unfortunately I have already replaced the transistor and it didn't fix the issue.

 

See additional tests suggested in my previous post.

 

Sorry, responded to early.

Could you explain how I can test for an open for the Blu/Blk, Blu/Red, and Blu/Yel wires. Also I bypassed the transistor, and it made the motor run.

Thanks

 

Did you bypass to the Blk ground wire?

 

Yes: BLK wire to BLU/WHT wire (https://troubleshootmyvehicle.com/ho...ower-motor-1#3)

 

Gotcha

Test the three previously mentioned wires for continuity between blower motor and power transistor or between power transistor and heater control unit.

 

Will do tonight. Do I have to remove the control panel to test continuity with the heater control unit?

 

If you can unplug the panel connector without removing the panel itself, then no because the continuity test is done from the connector.

If the three wires test good, then the heater control panel is likely bad.

 

Have you checked the blower motor relay?



What wiring diagram are you using?

 

The relay is on the power side of the circuit. OP clearly has a ground problem.

 

Yeaaaaah I didnt bother reading,my bad.




In that case,OP the ground circuit is very simple and so is the testing.

First make sure everything is plugged in prior to testing(a common mistake)

Make sure the key is in the ON position and the blower motor is in the ON position.

Turn the blower motor to the highest setting(it should run) and measure the voltage at the blu/yellow wire of the blower transistor(pin 1) You should have approx 8-10v.

If you have the correct voltage and no blower operation,the transistor is likely faulty

If you dont have the suggested voltage,the heater control panel is likely at fault.


There are other things we'll look at prior to replacing the control panel or transitor, but lets get the above testing out of the way first.

 

Ground side switched?
Power resistor was already replaced?
Then by looking at schematics, it seems to be the heater control unit?

 

I have done a little bit more testing.

I have continuity between the transistor and the motor and the voltage between on Pin #1 of the transistor varies between 0 and 15 mV, depending on the position of the switch (which makes me think that the switch is working).

I also did additional testing: I have 12V on the motor connector (BLUE/WHT) and 3.6 kohm on the ground side (BLK/BLUE). However when I back probe the connector and connect it to the motor, I get 12 V on both sides and an OL between the ground and the BLK/BLUE wire with the key in position II (with the key in position 0, i get 3.6 kohm between ground and the BLK/BLUE wire).

Could it be a short in the motor?

 

Motor works. Why would here be a short in it?

Motor is ground side switched.
There is a power transistor between the ground side of the motor and the ground.
When testing, hooking up a wire to ground of motor and ground, motor works.
Transistor has been replaced.
So, it is whatever is controlling the transistor that isn't working properly.
It has to be the control unit