I was wondering if anyone knows how to get the electric fan to turn on.Mine will only turn on once I've turned the engine off, and then it runs for about 20 minutes. I have no idea where or how it senses the temp. The car tends to overheat in traffic-like conditions and most all of the cooling system is pretty much new at this point (waterpump, radiator, temostat, etc.). Thanks

what kind of electric fan is it? trace the wires from the fan to find the switching source. it sounds like it's a bad temp sensor (different than water temp sensor that goes to the gauge) or maybe some wires got crossed.

I don't know the type offhand, but it is from motorsport. I've looked at most of the wiring and there is nothing that looks wrong, at least to my rather electrically novice eyes. Never thought of the other sensor though - maybe that is where the problem lies.

if it's an MSA fan, chances are the sensor is a meat thermometer-looking dealy stuck into the radiator. it may have fallen out....

Here's a picture of my sensor, it should try and go near the inlet hose between the radiator fins.

Good luck

You really need to determine the power source for the fan.

It can be either direct from the battery, or from an ignition type circuit [via protective fuse and relay].

The former will allow the fan to run at all times, depending on the fan thermostat/sensor operation.

The latter will be only when the key is in the "ON" position, plus thermostat/sensor operation.

Then, as mentioned above, the thermostat needs to be reliably attached to either the radiator metal work [e.g. top tank]or immersed in the coolant flow.

If the thermostat is adjustable, it need not be very complicated in its mounting since the device can be adjusted to switch the fan on at your desired temperature.

For it to come on ONLY when the engine is shut off is undesireable.

Either the power source is incorrect, or the thermostat is set far too high and only heat soak after shutdown is operating it:ermm: