Hi, I'm new here at honda tech, but I've seen quite a few post that have helped a lot with my 99 ex civic. But one thing that I want to figure out is, my radiator fan doesn't turn on, these are the things I've done so far:

-Changed the fan switch sensor, located in the thermostat housing
-Jumped the relay of the fan and it worked
-Jumped the fan switch connector with a paper clip and it turned on with car running but just sometimes, right now it doesn't
-Changed relays to discard faulty one
-I even changed the thermostat because it was stuck in the open position

Any help will be appreciated!!

 

The factory service manual has an excellent step-by-step troubleshooting procedure. It is well written and easy to follow.
That would be easiest way for you to solve this problem.

 

By jumping the relay contacts you are able to test the whole power circuit and it works.
The problem sounds like it could be in the control circuit that signals the relay to activate.
As far as I know, the relay control circuit should be hot when the key is on and the ground path is through the fan switch to operate.
Sometimes these cars have bad ignition switches and make intermittent contact for different branches to power stuff.
All of the ignition switch issues I have had with my civic and accords have been accessory branch related. Sometime my wife could turn the heater on and sometimes she couldn't. Wiggle the key a bit while it's still running and the heater would come on.
My civic would start fine, but the radio would not power up sometimes. Jiggle the key a bit and it comes on. Maybe you have an ignition switch issue. Check for +12v in the relay socket on the control side.
I hope this helps

 

Did you check the fuse for the fan located in the underhood fuse box?

 

Fact is the car (pre-owned) didn't come with the manual so this website is my main resource for solving problems with my civic, I will give it a wiggle and jump the connector to see if it toggles the relay and so the fan, also I will check the fuse corresponding to the radiator fan and then I will give you an update, thanks a lot!

 

You buy a factory service manual from a Honda dealer parts department.

 

Or download one for free on this magical thing called the....internet

 

The connector may be bad.

 

Ok I've downloaded the service manual, but all I can see is testing for ECT and thermostat, also the diagram for the fan controls and then a description of the cooling system, but not the troubleshoot I want, anyway...I will continue searching for another half hour x)

 

Did you miss these diagrams in the service manual?

https://honda-tech.com/honda-civic-d.../#post47713037

 

I took the sensor back to the store and got a new one and I dont know if it was failing and now it works but found out the relay had bad contact with the base so i fixed that and right now the fan works perfectly, thank you all!!