I have a 2004 Civic and the heater/air conditioning fan has stopped working, I have checked the fuses and they all seem to be fine, does anyone know what it could be that is wrong and how to fix this? thanks.

 

The motor on the fan could have burned out, in which case you would have to replace it with a new or working one.

 

Turn the key on but don't start the engine. Set the fan control on high. Check that the other functions of the control panel work. You should hear the motors behind the dash turn when you turn the air selector to different outlets. The rear defogger and A/C buttons should light up when you press them. If none of this works, check the fuses under the dash. There is a separate fuse for the control panel versus the fan motor.

If the control panel seems OK, take a voltmeter or test light and check for voltage between the two wires on the fan motor plug, the fan motor is under the dash on the right side. If you have voltage but motor doesn't run, the motor is bad. If no voltage, measure from each pin to ground. If you have 12 volts on both pins, the power transistor is probably bad. If zero volts on both pins, check the fuse and the relay under the hood.

The power transistor is mounted on the ductwork just after the fan. You will need to unscrew the hinges and take the glove compartment out of the car to reach it. Turn key off, unplug power transistor and jumper the two large wires on the plug, turn key back on. Fan should run full speed. If it does, replace power transistor.

 

Thanks for the info guys, this is actually my girlfriends car and I am just trying to help her get it fixed so she has some heat now that it is getting down to the low 30's outside. I checked the all of the dash buttons, the rear defogger, A/C, and air selector buttons, they all work fine.

Unfortunately I don't have access to a voltmeter so I wont be able to test the wires for voltage myself, is there an easy way to check if the relay is bad? all of the fuses inside the car and under the hood all looked good but as for the relays I wasn't sure how to tell if it had gone bad, I wouldn't have thought that after only about five years of moderate use that the fan motor would have died already but it is a possibility.

If it ends up being the power transistor can you get a replacement one at most auto parts stores or am I going to be stuck having to get it at the dealership? Thanks again.

 

Just wanted to let you guys know it was the power transistor that was the cause, I went to one of the local Honda dealers parts shop and picked up a new one for about $64 and installed it when I got home and it is now functioning properly, thanks again for the info.