Rep Power: 0

What's up everyone? I've got a 99 civic auto lx that recently the cooling fans will not come on. I checked fuses an relay then jumped/crossed the plug that connects to the thermo switch. Fans came on with key on (ll). I then replaced the thermo switch with same results. Any ideas on the next steps? Any info would be great. Thanks.

 
Rep Power: 518

You can jumper the wires at the switch for the fans and they run ok?
You replaced the thermoswitch for the fans?
So unless you got a defective switch it should all work, right?


You have the cooling system/radiator completely full and all the air burped out?


Maybe you aren't waiting long enough....If there is a breeeze it can make the fans take a loooong time to come on.

Maybe your temp gauge is lying to you?

 
Rep Power: 0

Yes the fans ran when jumped. So that tells relays an fuses are ok. I did change the thermo switch. After doing so I let the car run for a while to purge the cooling system. While doing so I hit the a.c. for a couple minutes an coolant Begin To Steam. Fans never came on. I was thinking that possibly there was still air in the system at the time?

 
Rep Power: 518

Did the condenser fan run at that time?

Does the condenser fan cover the radiator? (Most 6th gens have radiator and condenser set side by side and completely separate, but I've seen a full size radiator stuffed in there too.)



Steam? That's all?
It's HOT it can steam at normal operating temperature.

The fan may not run until the coolant temp at the switch reaches 203*F, and the temp in the top of the radiator can be significantly higher than the temp at the fan switch. Any breeze through the radiator can cause sufficient temperature drop to significantly reduce the need for the radiator fan to run.

Check real coolant temp on a scanner (my first choice), a thermocouple connected to a meter, a digital thermometer, or an infrared temp gun.