I had just the experience Barry refers to on my
spitfire with an aftermarket fan. The thermostat is a
piece of junk made in some backwater country (Where
the hell is the USB?...Oh wait that last letter's an
'A') And I did drain the battery once when it didn't
cut off.
Anyhow, I swapped out the thermostat for a solid state
(Taiwanese?) thermostat because the rusty mechanical
(?) thermostat would require a tap on it with a wrench
or screwdriver to get it react to the temperature
change of being cooled off. Usually someone from the
office walking in around 12:00 saying "terry, your
fan's still running."
Anyhow, a constantly running fan can keep your engine
too cool (and I'd leave the switch on accidentally
while driving on cooler days, I know it and kill the
battery repeatedly whenever I'd stop) And also the
temperature seems to increase when you let the car sit
for a few minutes (pressure cooker affect?). When you
run into the store for five or ten minutes, it's
actually hotter than when you got there. So I like
having a fan that runs for a while after I get out to
drop the radiator temp.
But now it's a b***h to change the temp setting on the
solid state unit because you need to adjust the temp
with a tiny screw driver on teenie tiny dial.
I got the new one from JC Whitney for like $40-$50.
-Terry
--- Barry Schwartz <bschwart@pacbell.net> wrote:
>
> >Engine cooling fans are typically fed by "always
> on" current, not from a
> >source that would require the ignition to be in the
> "on" position. The
> >reason for this is so the fans can run a while
> after the engine is
> >switched off (to speed cooling of the radiator once
> air flow from
> >vehicle movement is no longer present).
> ****************************************************
> While I *used* to have my fan switch this way, I no
> longer have it wired up
> like that now for other reasons. While I can see
> the logic, in that it
> WILL cool the radiator (and not much else when the
> engine stops running) I
> don't really see the *NECESSITY* for it. Granted
> there is a slight
> advantage in that it will help keep the water from
> boiling in the radiator
> but that's about it. After all in a typical engine
> driven fan arraignment,
> when the car is parked and the engine is turned off
> the fan, coolant flow,
> and airflow stops when the engine does - Hasn't
> harmed any vehicles in the
> past, and especially older vehicles that typically
> run at cooler temps than
> their contemporary counterparts (which may be why
> it's advantages in newer
> vehicles running up to 30 degrees hotter than our
> "old" vehicles) -
> That said there is really nothing wrong with either
> arraignment, and no
> advantage for cooling (other than that mentioned
> above) for wiring it to a
> constant supply. Actually, you would have a slight
> advantage with it wired
> "key switched" in the (admittedly EXTREMELY rare)
> event that the cooling
> switch stuck closed (hey it could happen), you
> wouldn't drain the battery
> from a constantly running fan :-)
>
> Barry Schwartz (San Diego) bschwart@pacbell.net
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