Is it normal for a cooling fan to start up automatically after every
trip, even in cold or rainy weather? I had the impression that it is
only needed after some serious engine loads and in pretty warm weather.
My Accord's fan seems to kick in for about a minute or so after a few
seconds following every trip, even fairly short ones that could not have
heated up the engine very much.
The fan is supposed to turn on after shutdown if the engine oil gets over a
certain temperature (240F? I forget). If the fan is coming on at times when
the oil cannot possibly be overheated, then the sensor is probably getting
old and is kicking in too soon.
A new one is about $40 at the dealer.
Thanks, as always, Tegger. Now, if it was as easy to replaced as those
alternator brushes, I would go for it. But isn't it also possible that
perhaps the radiator tubes have lost too much of their heat transfer
capacity (due to deposits) and that causes inadequate cooling? Probably
not though because the temp guage seems to work normally as it usually
stays below 40% of the scale.
Easier, I think. Except that it might need to be from under the car.
Were that the case, you'd have overheating at speed.
Then it's just a sensor. But I don't have diagrams to show me exactly where
the sensor is on your car.
If you feel like spending $10, you can get 3 days of all-you-can-download
from Honda's Techinfo site. You'll find the exact location of the sensor,
including replacement instructions.
I found that ECT sensor and it's impossible to get to without removing
the distributor. It's right under it and you cannot get to it from
below. either. Yeap, both the ECT sensor and ECT gauge sending unit are
under that darn distributor. There is an easily accessible ECT switch B
at the junction of the upper radiator hose and engine block, but I think
the sensor is the one that should be replaced. The ECT switch A, that's
also in a hard to reach location at the thermostat, is probably all
Since I see some oil leak at the distributor, I might have the mechanic
fix the leak and replace the ECT sensor at the same time. That job would
be over my head, I'm afraid.
I have access to the '94 Accord Service Manual and from what I could
find the fan control is tied to the ECT stuff. I haven't seen anything
on a separate oil temp sensor but I'll take another look. I'd rather not
pay for something I can get free. Even if I can afford it.
Does the fan also run if the A/C compressor is "on" and the ignition
set to "ACC" (or whatever it is, the manual is out in the garage)? I
could have sworn that on those 100+ days when I was auto-x'ing that
we'd pop the hood and turn the A/C on to cool the radiator between
runs. There's nothing like 100+ air, 130+ pavement and 30 or so
seconds of 1st & 2nd gear to warm up an engine.
I've been thinking (bad idea, I know)...
How would the ECU know if the oil was getting too hot after shutdown? After
shutdown, the oil mostly immediately runs down into the oil pan. The only
possible increase in engine temperature could only come from the water-
jacket area, where combustion takes place, and from where the oil would
mostly drain in a few minutes after shutdown.
Maybe the after-shutdown fan operation /is/ controlled by the ECT sensor
after all. Maybe oil temperature is just guessed-at by the ECU based on
after-shutdown ECT readings. After-shutdown heat-soak /is/ a known
Question for Cameo: Do you find that the fan comes on quite a lot more
often in general than you were used to, even with the engine running?
Well, I'm glad you realized that because I'd hate to disagree with the
Check these two links showing the relevant shop manual pages:
Since the fan cools the coolant by forcing air through the radiator
fins, it stands to reason that it is also controlled by the coolant
temperature, via electrical feedback.
As to your question, I don't know how the fan behaves with engine
running. I was only wondering why the fan would kick in shortly after I
park the car even after relatively short trips in cold weather. But the
fan does not run for 15 minutes as the shop manual implies. It only runs
one or two minutes, depending on the engine temp, I guess.
Oh, in regard to my earlier alternator brush replacement issue, I've
been checking the voltage during different electric loads and the
voltage seems to pretty much hover between 14.2 and 14.8 while the
engine is running. Even at idle. I find the following digital voltmeter
I can stick into the cigarette lighter socket quite helpful in this
<(Amazon.com product link shortened)>
The display actually shows the voltage with 2 decimal accuracy, not with
one as the above link indicates. The display part pivots and the shank
length is adjustable a bit, too. Very handy gadget indeed.
If the fan is running too much with the engine OFF, it should
also run too much with the engine ON.
If, that is, the same sensor is used to control the fan during
engine-off AND engine on.
Durng winter in a cold climate, the fan ought to run
very infrequently. It may never run at all if you're never
stuck in extended stop-and-go traffic.
I've never checked the voltage to that level of detail, but it's
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