Rep Power: 0

Greetings,

I just aquired a 1997 Honda Civic LX 4 Door with 160K. I got it fairly cheap because it is running hot. I plan to flush and Burp the cooling system after replacing the Thermostat and Radiator Cap.

It is my understanding that the cooling fan should come on when the A/C is Running. Mine does not come on with the A/C or when the temperature gauge climbs.



My Test Light Confirms a good fuse and I have power at the fuse marked "A" with the ignition on or off.

I can manually turn on the fan by jumping power to the pin on the Black/Red wire in the 6 pin connector labled "C"

I have no power at the female pin for the Black/Red wire in the connector labled "B" with the car running or not.

Is there some kind of relay or switch that tells the fan to turn on when the A/C is Running? Is there another one that turns on the fan when the temerature starts to climb?

Any input would be appreciated.
Thanks in advance.

 
Rep Power: 211

The radiator fan will only come on when the car reaches a given temperature. It's not dependent on the A/C turning on (though it could have an effect on when it turns on). Unless you're beating on the car or driving long distances the car won't reach the necessary temp for the fan to kick on. I'm almost certain the radiator fan comes on only when the thermostat opens, to cool the coolant leaving the engine. If the fuse is good, then the relay is working just fine and the fan will come on when it's supposed to, it just never needed to (yet).

 
Rep Power: 0

[quote=Zeferint;4568454]The radiator fan will only come on when the car reaches a given temperature. It's not dependent on the A/C turning on quote]

Thank You, The Honda Dealer in Shreveport Confirmed this for me too.

I replaced the radiator cap with the one from the Honda Dealer ($13). Now the car idles between 1000 and 2000 rpm like clockwork. It goes from 2000 for a second down to 1000 for a second and repetes the cycle over and over again. If I turn on the A/C it will Idle ata a steady 1600 RPM while the condencer fan is running. when the fan kicks off it will default back to surging. If I turn the heat to MAX Hot with the fan motor blowing it will Idle at a steady 1600 RPM the whole time. It has been Idleing for 30 minutes and not overheating at the 1600RPM.

I must have a sensor out or something.

I am a Honda Motorcycle and 4 Wheeler Tech, Not a Honda Civic Tech. I would appreciate anyones input into this problem.

 
Rep Power: 211

Idle surging is another indicator of a vacuum leak. Check vacuum hoses connected to and around the intake manifold for cracks in any of the rubber hoses. To do a real simple test, disconnect your brake booster line and put your thumb over it while the car is running. If it stalls, than it's not a vacuum leak. If it's not a vacuum leak, other indicators could be a dirty fuel or air filter, since the surging is a flux between a lean and rich mixture. The idle surging also points to a faulty IACV, which you mentioned earlier.

 
Rep Power: 0

Update;

Cooling fan comes on and off as needed.
My Idle surge problem turned out to be a seized up IAC Valve. It had a bunch of black crud inside of it. I soaked it in parts cleaner overnight and it free'd up the thing inside the rotates. Put it back on the car and it idles fine now.

There is a post somewhere dedicated the topic of "THE END OF ALL Idle Surge - Bounce - etc Problems Thread". That and a video on YouTube helped me complete the fix.