I've noticed recently that my radiator fan isn't staying on after I turn the car off. I tested it by turning the A/C up to max while sitting, and it does run then, and I haven't had any issues with overheating. I've done some searching, and haven't found anything specifically on this issue - any thoughts?

 

N18? If so, the DME considers three parameters to run the fan after turning off the engine: (1) coolant temp, (2) high-side refrigerant pressure, (3) turbocharger-related calculations based on length of drive, engine load/boost usage, and exhaust gas temps.

 

Thanks for your reply. Yes, it's an N18. My concern is that it's never staying on after stopping anymore, where it used to nearly every time I'd stop. The only thing that's changed recently is that I put a new clutch in, which I don't think should have any bearing on the issue. I'd suspect a bad sensor somewhere, but I'm not getting any codes, so that seems unlikely. Do you think I should be concerned?

 

Do you live in an area where the weather is hot, mild, or cold? Do you have scan tool that reads live data?

Do this: Start the car and turn the A/C on max cold and max blower. Does the radiator/condenser fan run at high speed under these conditions?

 

Mild - it's mostly around 70/75 all year. I've had the car for about ten years, though, and my driving patterns haven't really changed - I'm noticing that the fan doesn't run at shutoff at times when it would have before.

The fan does come on when I run the A/C on high at idle, so I know it's not a bad fan.

And yes - I do have an OBD dongle that will show live data on my phone. Is there something particular I should be looking for there?

 

Monitor the coolant temperatures from first start of the day to returning home. Do the reported readings seem consistent with expectations?

Do you ever see or hear your fan run on low speed?

 

If it turns on when the engine is cold, its the thermostat housing and sensor, or possible air in the top of the thermostat housing from a leak on the transmission.

If it run long after a drive and hot, its normal but only for track days or super hot days, like in the 80-90 degree all day.

Yep, check the readings and see if its going over 219 -225+ degrees after shut down.