The ac/heater fan in my 2003 Accord stopped working a couple of weeks ago. The car is mostly driven by my daughter so I was not particularly in a hurry to fix it but I feel bad now to see her leaving every morning for school in the cold weather and driving her car with winter gloves, scarf and ski hat .
I am going to have a look at this over the week-end but wondering if you guys had any good input for possible causes beside obvious things like fuse or blown fan motor.
Thanks
Al

 

you should post this in general tech

 

I'll move it to Gen.Tech.

 

Before you get into what it could be start with the basics, have you checked the fuses?
That would be the first thing I would look at.
If all the fuses are good I would turn the fan on and check the wires going to the fan under the glovebox area and see if you have +12 volts on one of the wires.
Check those things out and report back if you still need some help.

 

And check out this thread...
https://www.hondaaccordforum.com/for...-2006-a-36131/

 

Thanks folks for your quick response. Yes fuse and wiring is the first thing I will check of course. I was just wondering if there were other things beside that which are known to fail on a 2003 Accord related to the fan.

Jim, thanks for the link very helpful

Al

 

I've seen postings about failed blower speed control unit. It's a solid-state $$$ unit, so you'll want to rule out wiring problems before buying one. That's why I posted the wiring checks. They came from a 2003-2006 Helm shop manual. I don't own the 2003 Accord any more so I sold that book a couple years ago.

 

I have done some research based on your help. Fuses are ok, the blower motor is ok. I powered it directly with a 12v source and it works great. As far as the blower control switch (called power transistor in this thread) is concerned I am not sure if it works or not. I did the tests that James is suggesting in his post with the following results but I don't know what I can deduce from that.

I unplugged and removed the blower power transistor which is located underneath the dash on the passenger side. I measured the resistance between the 2 wires farthest from the latch on the blower transistor and I got around 1.4k as James's note indicates as correct. As instructed in James's note I remove the #1 wire BLU/YEL from the blower resistor plug, supplied +12v into the empty socket where that BLY/YEL wire was before and turned the key on. The blower did not run.
I am not sure what to conclude. Is the blower power transistor the faulty part or is it upper in the circuit that there is a faulty component.
Thanks
Al

 

Check for HVAC Codes. Here is the link:

https://www.hondaaccordforum.com/for...-code-s-34589/

 

Check the black wire (end of post #1 in that other thread). Is it a good ground?

Check the blower motor itself (see post #2) by touching the blue/black wire to ground. If that doesn't make the motor run, then you have either of 2 things...
1 - Blower motor isn't getting power like it should (check fuses, etc)
2 - Blower motor is bad.

I wish I still had that book so I could look at the circuit diagram again...