My 2001 Civic HX has been giving me some problems. Recently my ac/heater stopped blowing. I checked the fuse, relay, and even tried connecting a new blower motor (didn't work). The really weird thing is that it was not blowing for about a month, then all of the sudden it worked for a day, then stopped working. Along with this, my car alarm usually doesn't work (won't beep horn when I lock), but a couple of weeks ago it worked for about 5 days. I'm wondering if these things are related and indicative of a bigger problem. Anyone know what could be going on? Thanks.

 

If the heater control panel is working (you hear the motor behind the dash move when you change the air flow modes for example), it's probably the power transistor for the blower motor. This part is located behind the glove box mounted in the air duct with a 4-wire plug. Unplug the transistor's plug and jumper the two heavy wires, the fan should come on full blast when you turn the key on. If it does replace the power transistor.

Is the keyless otherwise working (lock / unlock, lights flash, etc) except the horn doesn't blow? In that case try the horn from the steering wheel button and if it doesn't blow it's probably the horn itself rusted out. Or the fuse is blown.

 

The horn works from the steering wheel and the keyless locks/unlocks the doors and turns on the dome light. I just don't hear the horn when I lock anymore.

I definitely don't hear anything from the blower motor when I turn the dash control. I did notice that I hear some kind of fan that sounds more like it's coming from under the hood. I put the key in and turn it with the fan off. Then, when I turn the fan dial up, I hear that fan under the hood for about 5 seconds, then nothing.

Any ideas? This really sucks because we're going on day 2 of heavy snow and sub-32 degree weather here in Denver.

Thanks.

 

Install the jumper like I suggested. That should make the fan run so you have some heat. If everything else works OK go ahead and order a new power transistor. You will need to remove the glove box from the car (by unscrewing its hinges at the bottom) to reach the power transistor.