99 Civic LX - Cooling Fan Not Turning On
 

The radiator fan is not turning on.

I let the car run for about 10 minutes, but the radiator fan is not turning on.

I jumped the fan directly to the battery, and the fan worked.

I paper-clipped the wires that go into the thermoswitch, and with the ignition switch turned to On (II), the fan was working.

I replaced the cooling fan switch, ran the car again, but the fan was not turning on. Currently, I put the old switch back on.

What else can I try?

Thanks

Is the engine overheating?

It can take a long time just idling for everything to heat up enough that the fan must come on. Test drive with the new switch, or with the paper clip in so the fan runs all the time. If it doesn't overheat, the switch was bad.

If there is no flow through the radiator (e.g. thermostat stuck closed, or lack of coolant) the fan won't come on. So the engine can overheat without the fan coming on even though there is nothing wrong with the fan system.

The engine is not over heating. The radiator is leaking, but I keep adding coolant and the leak isn't too bad yet.

The lower hose gets hot, so I am assuming that the thermostat is letting it through and that there is enough coolant.

Given that it doesn't overheat, what do you suggest?

Thank you.

Replace the leaky radiator obviously. Don't try stop leak, it doesn't really work and is prone to stop up your heater core, which is expensive to replace.

Everything else sounds like normal operation.

Thank you. The fan finally turned on yesterday. I think it is probably fine.

I am replacing the radiator today. Would you recommend replacing the thermostat and thermoswitch at the same time as well?

How did u get it to come on? I'm having same problem. I have seen fan kick on twice, at fast idol coolant temperature was about 210 degrees , and it only stayed on for 10 seconds.

I am not an expert, but maybe 10 seconds was enough to cool the system?

The fan on my car comes on after about 20 minutes and when an IR thermometer pointed at the thermostat housing reads about 200F. I think that it doesn't stay on for longer than 10-20 seconds.