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Cooling fan in winter?

Is it typical for an electric cooling fan to run in the dead of winter, even when not driving in stop and go traffic? The fan on my 2001 Forester is coming on even when it’s 10-20F outside. It seems to run for a long time too.

Let’s say that the dash engine temperature gauge is correct. Does it indicate about half way? Or, is it showing low engine temperature? If it’s low indication, the engine cooling fan relay may be sticking. Many relays are the same type. You could swap it with another relay…maybe, the horn relay. Check the coolant level in the radiator, when the engine is cool.

The temperature gauge is where it usually is, just above the halfway mark. I’ve noticed the fan running more since the timing belt and water pump were changed recently.

Then it is working normally.

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If you’re using the “defrost” setting, or directing any air to to the windshield, the AC compressor will be engaged. When the compressor switches on, the radiator cooling fans also switch on. The radiator may not need cooling, but the fans will run anyway. This is part of the NORMAL operation of the HVAC system. Don’t worry about it.

Thanks It’s happening w/o those settings being engaged.

If you have built up snow or slush blocking your radiator, it could cause your engine to run hotter than usual, although within normal range, and the fan will kick in. If so, nothing to worry about. Has it been snowing where you are?

No snow - no blockage. A new thermostat was put in when the timing belt and water pump were changed. It’s 18 degrees in Cincinnati and I just returned from a 20 min. trip @ 35-45 mph. The fan was still running when I pulled in the driveway. Subaru says the fan kicks in when engine temp reaches 203F.

It sounds to me like everything is working fine. Realize that the engine compartment is a lot warmer after the engine heats up than the outside air. It’s a semi-closed environment. And with today’s tiny radiators, small grill openings, and lots of stuff stuffed around the engine, then as long as it’s been looked at and the engine is maintaining proper operating temperature I wouldn’t worry about it.

Remember, todays’ systems don’t just keep the engine cool, they keep the engine at an optimum temperature. They only remove huge amounts of heat when huge amounts of heat are generated. Besides, if you have your defrost on your system may be turning on the AC in the background to remove moisture and that could be causing the secondary (AC) fan to operate. Lots of cars do now. I’m not sure about your setup.

There should be only one setting on the mode control in which the air compressor and cooling fans will not come on and that is the HEAT position.

It was 14 last night in Cincinnati and I was driving @ about 40 mph on the highway and the cooling fan was running with the mode control just on “heat” only. It doesn’t make sense with the outside air temp. What if the new thermostat has an “opening temperature” that’s higher than 203 deg. (temp at which fan sensor kicks in)?? Wouldn’t that cause the fan to come on. I need to check what Subaru calls for re. thermostats. Maybe the NAPA one opens at a higher temp.

Your on the right track, i installed after market thermostat, made my system run more often, the spring on the aftermarket was very loose and would therefor open prematurely to not oem specs causing the system to run the fans more often and longer intervals. When i installed the oem thermostat, back to normal, the fan ran 30-45seconds at normal intervals. It should he noted also, the oem thermostat spring was much tighter, i needed four fingers on top and thumbs on bottom to squeaze it open.

Wouldn’t a thermostat that opens early cause the engine to run cooler- thus less need for the cooling fans to run?

No, the opposite is true, if the thermostat opens frequently, then the liquid will flow, when it flows, the fans will turn on to cool the fluid down. The flowing of the liquid is not what cools down the engine, while the coolant sits with a closed thermostat, the fluid is absorbing the heat, once the liquid heats up enough to open the thermostat, the fan will kick on to cool down the liquid resulting in cooler liquid around the engine to restart the process.
Thanks for posting back. hope this clears this up.

Sorry Jayjay_Oner, but …
I really hope nobody takes this serious as it is wrong in so many ways.


It does , it shows you have no idea what you are talking about after digging up an old thread.


Nah, you just simply do not comprehend simple English, i should have realized that from your first response, my mistake.

I don’t know whether VOLVO_V70 comprehends simple english or not, but You don’t comprehend how a cooling system in a car works and even prove it by showing it to the public.


I’m guessing the problem has been resolved for better or worse after 11 years.

You are also completely backwards in your logic. The thermostat opening too early will result in the engine running cooler than spec. It will NOT cause the cooling fan to cycle longer or more frequently.


Right. Pretty easy theory to prove. Take out your thermostat. Engine runs cooler. Put in a thermostat that opens at a lower temp than stock. Engine runs cooler.

One caveat - the engine will run cooler until the capacity of the cooling system is reached. In other words, the engine will eventually reach the same temp (hot) even without a thermostat if you’re towing a sailboat in the desert Southwest in summer. Or probably even if you’re just driving in the desert Southwest in the summer.

Old thread, I was bored.