torontob

Hi Everyone,

I own a Honda Civic 2009 DX-G 4DR which has about 111,000km on it. I have on two occasion noticed the heat indicator go to red and so I turned off the AC (this all happened in past summer) and the engine cooled down. Upon inspection, I noticed that my passenger side fan (the one right behind radiator) never comes on. I understand both fans should turn on once the AC is turned on. Please let me know where to start to diagnose this. Please let me know what tools I need to check the harnesses or fuses etc....

Thanks

ezone

Turn the AC on so both fans should (supposed to be) run.

Inspect for B+ AND ground in the connector for the fan that isn't working.

If both are present, then you need a fan motor.
If one is missing, you need to get a wiring diagram and tools to figure out why.
Fuse, relay, input signals, etc. All are easy to figure out with a little basic understanding, a few simple tools, and a wire diagram.

Or give it to a professional before you do serious engine damage from overheating. They will warp the cylinder head in an overheat. That damage is on you for not fixing the fan.

torontob

Thanks. Turning AC on doesn't turn both fans on. Should this be under warranty? Car was bought June 2009 and it's 111,000Km now.

What is the B+? one of the wires from the fan to the fuse box or battery?

I can trace cables and wires...pretty tech savvy (which I guess makes me mech savvy as well :-)

Thanks

ezone

Read your warranty terms.
US cars have 3/36 bumper to bumper and 5/60 powertrain coverage from the factory.

B+ stands for battery voltage positive (as opposed to ground).

Both fans ARE SUPPOSED to run with the AC on.
I KNOW one fan doesn't run.
Turning the AC on SHOULD power up the fan so you can check for power and ground on it.
Any electrical device has to have at least a power and a ground to make a complete circuit and operate.