hello,

2002 civic lx

the radiator fan is not coming on
I have shorted the 2p connector for the coolant temp switch and the fan does not come on with the ignition switched to on.
If I turn the ac on both the condenser fan and radiator fan come on for a few seconds and then turn off.
If I run a hot wire to the battery from the radiator fan, it will stay on. So I know the fan is good.
I switched the horn relay with the radiator fan relay (identicle part numbers) and get the sam results
fuses are good

Does anybody have any ideas?

Thanks in advance for any assistance!

 

The 2P connector for the radiator fan switch has a hot Grn/Wht wire and a Blk ground wire. With the key in ON(II), does the radiator fan run if you ground the Grn/Wht wire terminal to the body frame?

 

This really has to be a problem with the plug or the wiring. When you turn the A/C on the ECU pulls the green/white wire to ground, energizing the relays and starting the fan exactly the same way as if the coolant switch had closed.

Like Ron said, check the ground. Also with the key on (fans off) you should have 12 volts on the green/white wire. If not there is an open circuit between the fan switch plug and the relays.

 

Thanks for the info, I will check this when I get home this evening and let you know.

 

okay,

finally got to do some more testing today.

Actually the wire colors for my car on the 2p connector is:

Brown/white (5v) with key in on position
Green/white no voltage at all

on the radiator fan the wires are:
blue/black
black

I am not getting any voltage to the fan except when the ac switch is on I get voltage for about 30second and then it is gone?

I am the original owner of this car and the only mod to the car is an aftermarket radio, which has been in the vehicle for about 3 years

Does anyone have a wiring diagram for the cooling system? I read on one forum that there might be a timing switch under the passenger side kick panel. I did not take this out and look as the article was for an accord and not a civic.

I did not ground the 2p connector to the chassis since the wires are different colors than the ones suggested.

Thanks

 

This is the sensor on the thermostat housing (where lower radiator hose meets the engine)? It sounds like you are at the one on the head. That one does not control the fan. It is connected to the ECU and runs on 5 volts so that would make sense.

If you look back to last week or so where someone was having a problem with his 2002's A/C, there is a diagram posted in that thread that shows the fan circuit.

 

well, so I was testing the wrong "fan switch". When I tested the correct fan switch it turns out to be the problem. Thanx for your help and showing me the err of my ways!!!