Schlef

2002 Honda Civic EX.

Ok, weird problem. I ran through all the diagnostics, and the diagnostics indicate I have a bad blower motor. Fortunately, I replaced it a few years ago due to bad bearings. However, it doesn't work on the new one either.

So I figured I'd do my own trouble shooting. I ran a lead from the + of the two pin connector to the blower motor, and the - of the blower motor to a body ground. Fan spins up just fine. Checked the voltage, and it is around 12v.

I think, maybe I have a bad ground? I did a continuity test from the - of the two pin connector and the O.L. goes away.. so I have continuity to the ground. I

then ran a lead from the - of the two pin connector to the - terminal of the blower motor, and a lead from the + of the two pin connector to the + terminal of the blower motor (yes, this is essentially plugging it in), and at the II position, the fan makes a small twitch and stops.

I have no idea what could be wrong at this point. I have 12v coming out of the + pin of the two pin connector, and I have continuity to the ground from the - pin of the two pin connector.

What am I missing?

Thanks in advance.

mac25

You may have done this but, food for thought...

-Turn the circuit on
-connect a new wire from the body to the blower ground.
-if it does not turn on then you know it is an issue with the positive side of the circuit.

You have already verified that all components of the circuit function...

that leaves one last component, the wiring.

Trace back the circuit from the blower motor back, on the positive section of wire.

Use a multimeter to determine continuity of the positive wire segments.

Make sure to disconnect the battery and the ground wire to the blower motor, or you could get a false positive as the multimeter could sound off for continuity by looping through the battery to the ground; rather than through the wire segment desired to test.

ezone

Do the same check by backprobing the terminals with the fan motor connected. See which is missing, power or ground.

If ground is missing-- inspect the power transistor.

Schlef

Good idea. I'll try that. I did already test my power transistor by following this guide:
http://troubleshootmyvehicle.com/hon...esistor-test-1

I cleared Test 1 and 2 with flying colors. I didn't have the AAA battery, so I didn't do the final test. I'll give it a go though.

Thanks.

Schlef

Sorry, I'm a bit new to electrical problems. I ran from the positive end of the 2pin blower connector to the positive of the blower motor, and the negative of the blower motor to the ground. And in that situation, the blower motor works fine. Does that mean the positive wire tests aren't needed?

Good call on the battery. To check the negative connector segement, should I be doing a continuity test from the negative of the 2pin blower connector to the negative of the battery or to the ground? I'm assuming I should actually be doing the negative terminal of the battery.

Thanks so much for the help.

ezone

Unplug power transistor. Turn the key on.
Jumper the two fattest wires in the connector (this supplies full ground to the fan motor) Fan should then run full blast.

You don't need to leave it running, as a couple seconds is plenty of time to confirm the fan actually runs.
(If you use a paper clip as a jumper.....it may turn red hot and sear your fingers.)


You could open up the power transistor cover and check the TCO to see if it is open circuit.
(I have several of these units that have been "fixed" to use as test parts)

Schlef

Jumped it, fan turned on. I was pretty happy to have nailed this down. Went to Advanced and bought a new Power Transistor (Santech branc), installed it, and it worked! But..

On the way home I stopped in at CVS. After starting my car back up, I'm having the exact same problem, fan doesn't come on. I got home, disconnected the connector, rejumped the pins, and fan starts working again. So..

As far as I see it, either some other component is destroying the Power Transistor and killed this one too, or I got a defective Power Transistor that failed after the first use. Thoughts on likelihood of each scenario?

ezone

Did you actually install it in its hole, or did you just connect it and leave it dangling by the wires?

It MUST be installed in the housing so it will have airflow across the heat sink, or it will be ruined quickly.


Also check the cabin filters....if those are clogged up that can block much needed air flow.

Schlef

Hahahaha.. um.. was not installed in the housing for the ride home. Dammit. I'll assume that I wrecked it. I'll let you know otherwise.

Thanks. I've used the form a lot for getting information, but never had to ask a question. You guys are incredibly helpful. Send me a PM if I can send you a tip.

ezone

Warranty! Don't tell them what happened....
How did I guess that one right?



LOL...Surely if you've read the forum a lot you've seen me post the pic of that guy above many times

Schlef

My cabin air filters were not in ideal condition either, not awful, but perhaps contributed to the first one going.

I live in Florida, so considering taking a fat wire and jumping that for the drive to work in the morning.. and I know this already sounds like a terrible idea.

ezone

Meh....the original part went bad just because they all seem to eventually go bad regardless of the cabin filters condition....but it's a great time to check them and point fingers anyway.

You don't want a poor connection to overheat the terminals in the harness connector, nor do you want to do anything that would spread out or loosen the grip of those female terminals in that connector.