2003 Accord Motor Blower not working
 

2003 Accord 2.4L EX AT

My blower motor did not come on the other day and it doesn't blow at any speeds. I read the DIY here https://www.hondaaccordforum.com/for...-2006-a-36131/ and have been able to complete some of the steps.
checked that the blower motor was receiving 12V (white/blue wire) - yes
checked the motor blower fuse (#21) - good
checked the under dash fuse (#30) - good
swapped out the 12V blower relay with another 12V relay - relay is good
tested the blower motor resistor amperage draw - 1.4k ohms

I also tested the blue/black wire going to the blower motor and it read 12 V, just like the white/blue wire when the car was on.

checking the blue/black wiring from the motor blower to resistor showed 12V.
applying ground to that wire did make the motor blower come on.

I haven't performed any other tests at this time. I initially thought the the resistor couldn't be the problem after reading that the blower should still work when the fan setting is on high (by-passing the resistor), but maybe this was for a different model.

My question is, have I narrowed the problem down to being the resistor or is there other possible problems?

Thanks!

If you applied ground to the Blu/Blk wire, the blower should have run since 12V was present indicating power was supplied to motor via Wht/Blu. This bypasses the power transistor to provide direct ground.

Since motor did not run, this indicates a faulty blower motor, probably worn brushes. Sometimes you can thump the motor case firmly and motor will restart temporarily. If this happens, bad (loose, worn) brushes are confirmed.

good luck

I think you may have misread what I wrote or maybe I misunderstood what you wrote. The motor blower did come on when I applied ground to the Blue/Black wire. Does this indicate that the resistor is most likely the problem?

Sorry, I misread.

This indicates power transistor is open and not allowing a ground path to enable blower to run. Power transistor is a variable resistance to control current flow/speed of blower.

good luck

The old resistor block would have a working fan if the highest fan speed setting was set.

Your car has a transistor to control the resistance, so it controls fan speed differently and none of the fan speeds would work if the power transistor fails.

In the common diy thread on top of the gen tech help forum, there is a link to checking hvac codes for the 03-07 accords. Try this procedure and let us know if you get a code (I believe a code N indicates a problem with the power transistor).

Thanks for the good information. I'm trying to understand the problem as much as I can for future reference. Would you say that since the ohms tested within range that there is some other component (other than the resistors) within the transistor that is bad or just some faulty wiring within the transistor? I will probably try to open it up tomorrow and see what I find.

Do you know what generally causes these particular transistors to go bad? It seems like a somewhat common problem on the accords from looking at the forums and youtube videos.

PAhonda, I just saw your reply. Really good information to know about the old resistor blocks - that was no doubt what I was reading about... I will try to check on the codes tomorrow.

The transistor fails because chip inside fails and generates enough heat to blow a thermal fuse.

I looked into it, but the chip was not easy to find anymore.

There is a post floating around on here where someone "repaired" thier old one. From the "Common DIY Threads" sticky at the top of this section: https://www.hondaaccordforum.com/for...96/#post243753

PAhonda, I don't have automatic climate control, so I can't run the diagnostics steps as they are presented in the DIY thread.