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Radiator Fan became super loud and won't shut off

I have a 2003 Mitsubishi Outlander. About two months ago, I replaced (myself) the radiator fan because it had stopped working. I bought the new fan on the internet and it was fairly easy to install. It was a little louder than the original fan, but it worked great. Last week it suddenly became louder and stays on for a minute after I turn the car off. Is the fan defective? Should I return it? Should I ask my mechanic to test it? Or just ignore it?

Thanks!

It is not unusual for a cooling fan to keep running for a minute or two after you shut the engine off, as its running is determined by the temperature of the cooling system. This may–or may not–be a sign of a problem.
Quien Sabe?

As to returning the fan two months later, I think that is determined by the return policies of the company from whom you bought it, so checking on that company’s return policy is probably a good thing to do before any more time elapses.

I think that a visit to a competent mechanic might be in order at this point, but, again…Quien Sabe?

I don’t think there’s a problem.

The fan is contolled by the coolant temp sensor, the fan relay, the ECU, and the fan contoller. It’s not unusual for the fan to run after the engine is turned off. And if sounds louder it just means it’s pulling a lot of air thru it.

Tester

I agree with the other answers.

Some vehicles will turn the fan on after the vehicle has been parked for a while. It’s because some engines actually get hotter due to “percolation” after they have been parked. When I lived in Arizona, I could hear car fans turning on and off in the parking lots at various times during the day.

Thank you. It is cold here so I am thinking something is wrong with it for sure. It also comes on and stays on first thing in the morning even if I just turn the key on and right back off. My final question, can it hurt anything? Is it okay not to get it fixed?

Does the engine warm up? It won’t really hurt anything if your engine reaches operating temperature. If not, there could be problems.

Yes, the engine warms up. Everything else appears to be the same. Good coolant levels, etc.