fans continue to run after motor shut off...

detcord · #1 (**permalink**) 03-01-2005, 02:25 AM

Wifey is telling me that this afternoon her radiator fans continued to run for about half a minute past the time she shut the motor down. She can't tell me if the temp indicator was hot or cold ( you know how chicks can be sometimes ).

Anyway, checked it out this evening, T-Stat appears to be opening and radiator appears to be removing heat. Fans cycle on and off with A/C compressor, and when I shut the motor down fans went off as well. Just wondering what this could be, any ideas appreciated.

BTW I plan on doing the ECT sensor replacement ASAP as she gets crappy gas mileage, and she drives like a grandma. If the motor kicks down to a lower gear she thinks the gas was pressed too hard.

Thanks.
Detcord.

97altydriver · #2 (**permalink**) 03-01-2005, 03:02 AM

My car does the same thing except mine stays on for about 1 minute after I turn off the car. On my way home I stopped in front of my house, got the mail and put the garbage cans away. It took about 5 minutes. When i got back to the car the fans had turned off. I started the car and moved it to the back of the house(about 50 feet) and the fans stayed on for about 45 seconds after I turned the car off. I have no idea what could be causing this, but I am leaning toward the coolant temperature sensor(CTS). And BTW my temperature gauge is always where it should be.

Magoo · #3 (**permalink**) 03-01-2005, 03:25 AM

That's normal.

JLewisinSyr · #4 (**permalink**) 03-01-2005, 04:56 PM

Very normal, its the car cooling itself down after its shut off, my Lincoln does the same thing, actually a lot of newer cars do.

detcord · #5 (**permalink**) 03-02-2005, 12:15 AM

Thanks guys,

I should have added to the first post that this is a 97...we've had the car for about 4yrs and I have never heard it do that before. I will say though that this motor seems to run hella hot!

Again, Thanks Much. If we were talkin Tacoma's I'd be ok, but this Altima is a new species for me.

FrAnCoOo · #6 (**permalink**) 03-02-2005, 04:19 AM

yea i was gonna say i thought most cars do that

**jserrano** · #7 (**permalink**) 03-02-2005, 05:14 PM

Newer car are programmed to do this but only you would know whether your car behaved this way before. Here is thread where someone replaced their ECT and fix this "problem",

http://www.nissanclub.com/forums/sho...d.php?t=183757

yasar · #8 (**permalink**) 03-03-2005, 06:56 PM

its normal, i believe the fan stays on afterwards to take away any condensing? pretty sure thats for a/c operation but i don't know about this case. all that i know is that its normal

TriniVinci · #9 (**permalink**) 03-03-2005, 08:33 PM

def a common thing in 98-01's... mine is no exception

97altydriver · #10 (**permalink**) 03-04-2005, 12:21 AM

Quote:

Originally Posted by TriniVinci

def a common thing in 98-01's... mine is no exception

Is it common in 97's?

canoner · #11 (**permalink**) 03-04-2005, 12:30 AM

I had a 94 accorde that used to do this. It turned out that the radiator was leaking and I fixed it.

Frea_Kanata · #12 (**permalink**) 03-26-2005, 01:48 PM

seriously..look out, my car started doing it to and i also have a leaky radiator. beware, it might be a serious problem down the road.

SLOW KA_ · #13 (**permalink**) 03-26-2005, 02:52 PM

Quote:

Originally Posted by TriniVinci

def a common thing in 98-01's... mine is no exception

yesir

Pulski · #14 (**permalink**) 03-26-2005, 04:43 PM

Common. It depends on what kind of driving you've been doing, but otherwise this is normal. (I also have a 97)

deadrx7conv · #15 (**permalink**) 03-27-2005, 09:24 PM

I've seen and experienced this issue. Its not normal. Most people did not experience this problem when the car was new.
With Consult plugged in, two identical Altimas measured different head temperatures. The Altima with the fan run-on problem had higher coolant head temperatures of almost 20 degrees. The other ran cool. BTW, this took 16 hours to diagnose and the customer vehicle turned into a technician daily driver for a couple of days.

This issue is becoming more common and can be caused by several things.
Dirty rust/scale/deposits usually removed with flushes caused by not changing the coolant regularly.
Failed thermostat easily replaced with new Nissan OEM thermostat. Thermostats may open partially and may appear to work even when failing.
Slipping water pump belt. If over 30k miles on belt, replace or tighten it.
Defective water pump. Tough to diagnose. Check for loose pulley, pump noise......If over 100k miles, just replace it.
Defective coolant temp sender which sometimes gives off SES/CEL.

The coolant recovery bottle is also a settling tank(think passive filter). Clean the recovery bottle. The crud coating the recovery bottle is the same crap coating the insides of the engine and radiator. Checking this 1st will verify a dirty cooling system.

Start with a new OEM thermostat and a flush using zerex/prestone/wynns flush chemicals. Or visit the dealer/quicklube for a machine antifreeze exchange. A common one is the Wynns flush. It is very important that the shop does NOT use a leak sealer which is common with an antifreeze exhange. A typical stop leak radiator product will increase the likelihood of the problem.
If you do the flush yourself, do not use tap water. Wallyworld sells distilled water for $.60 a gallon. Buy 12 gallons. This will allow you to flush the radiator/engine multiple times.

I find that the flush/thermostat/belt will fix most cars. The temp sender and water pump seem to be the least causes of this problem.

One vehicle required 4 Wynns type flushes over 4 weeks before eliminating problem. Each antifreeze change had numerous particles floating in it. These particles were similar to what was in the recovery bottle after shaking it vigorously filled with water.