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Cooling fan runs too long I think
Hi All, I have a 2009 Versa 1.8L six speed. The radiator cooling fan runs what I think is far too much. It's not on continuously, and takes quite a while before it comes on (perhaps 5 miles of regular driving), but after it's on, it hardly ever shuts off. In particular, if I'm driving highway, where I would expect the air movement to render the fan unnecessary, it still doesn't turn off. On the other hand, sitting in traffic, it might. It does not, however, seem to boil over, although I'm anxious because it's the cold season here in Colorado, and when we get to Summer again... Well, you get the picture.
I have attached an OBDII monitor to this while driving, and what I see is the coolant temp slowly climbs (fan is off) till it reaches about 100C. Around about there, the fan comes on, and then with the fan basically running continously, regardless of driving conditions, the coolant temp will vary between about 101 and 106 at the extreme, staying mostly in the range of 102-104.
Now, I see that there are two thermostats sold by local stores for these cars, one with an opening temperature of 180F and one at 200F. I believe that these two are both used in the same engine (one controlling the cabin heat), but the 2009 Versa manual shows a single thermostat with an opening temperature of 180F.
My suspicion is that the young lads who owned this before me probably put the 200F thermostat in when the replaced the radiator after a front-end collision they clearly patched up themselves.
Does this guess seem plausible to others, or is there a more likely explanation for this seemingly controlled coolant temperature that also seems to be higher than the engine computer wants it to be?
I guess another explanation would be if the thermistor that measures temperature is out of calibration and it's not really all that hot, but the computer thinks it is. But I'm not sure that a thermistor is a device (being a solid state electronic part) that's particularly prone to wandering calibration is it?
Any thoughts welcome; I have the thermostat coming ('coz it's cheap) but draining the system and replacing it will be a bit of a nuisance if there are other things I should be trying first...