Hi, I just returned from a road trip up north and back and the entire time the heater-a/c fan was working fine. My wife drove the car (2004 EX) to work yesterday and found the fan wasn't working. The a/c light comes on but nothing else. I checked the fuses under the hood and all are ok. What else could it be?

 

fuses under the dash or a relay?

 

as hatch says, check the relays too.

 

The fuses checked out ok but I don't know where the relay for the fan is. I checked the relays under the hood and a couple of the relays behind the glove box and they seem ok. Does anyone have a diagram where the relay may be?

 

First try to retrieve a DTC (picture 1). Post any DTC you happen to get.

Supply power directly to the blower motor to ensure that it works.

Next test the blower relay (picture 2), the power transistor, and the blower switch itself.

 

Thanks Ronj, I was hoping you would chime in. You helped me several months ago with the door locks on my daughter's 98 Civic.
I ran the diagnosis and the DTC came back with 12 blinks. Do you happen to know what that means?

 

 

Wow, who needs a mechanic with you around? Thanks so much. It's bedtime here so I will have to finish diagnosing the problem tomorrow night after work. I will let you know what I find. Thanks again.

 

RonJ, you've done it again
With the information you posted here, I was able to troubleshoot the problem and found that the power transister module was burned out. There is a "Honda only" salvage yard not too far from me so I swung by there today and picked one up for only $25. The cabin air filters were almost totally clogged and were probably the reason the transister burned out. I've never owned a car with these filters before this one and I didn't know to change them. The blower now works and I have new filters so I'm good to go! Thanks again, Murray

 

Congrats wearelove! Isn't RonJ incredible!

I believe those cabin air filters became standard on car post 200* I'm not sure the exact year but my 2003 Windstar has them too. Need to be changed every so often. It sure makes the air in the car good if you don't roll down the windows.