Cooling Fan Problem, 91 SC2

I just bought a 91 SC2. The cooling fan stopped working so the guy who had
it installed one of those adjustable fan controls. He seems to think the
computer is the reason why the fan doesn't work. I would like to fix what
ever the problem is, so that the fan works the way it should. Could someone
please explain the proper procedure to pin point the faulty componant. I
hope I'm not asking too much. Please help.

Thanks,
Dennis

 

Your model is an SC, not an SC2. In 1991 & 1992, the coupe only had the
dual cam motor (no single cam option existed), and its designation was
simply the SC. There were no SC1 and SC2 designations in those years.

You NEED a Haynes or Chilton manual for your car. You can pick up one from
any auto parts store for around $10. It will give you troubleshooting
procedures and wiring diagrams.

The fan usually only turns on when the temperature indicated on the gauge
reaches either 3/4 or the red (can't recall which - do a google groups
search of this newsgroup and you'll find a lot of info on the subject).
Only then is the fan supposed to come on. Most people think the car is
running "way too hot" or "overheating" when they see that level on the gauge
and realize the fan is not on and that's an incorrect assumption.

The fan also comes on when you turn on the A/C, but the A/C will only turn
on when the outdoor temperature is above a certian point (Haynes or Chilton
manual would probably tell you what that is). I've never heard of the PCM
going bad in such a way to make the fan control not work correctly. Most
often, people report here that it is one of the temperature sensors.

Good luck,
Lane [ lane (at) evilplastic.com ]

 

Thank-you. I have a manual ordered.
I've never seen a car that was so hard to identify. The person that I bought
it from wasn't even sure what model it was.
The title said it was a GL or something I can't remember for sure. So thanks
for clearing up the mystery.

Dennis

 

There is a good chance that the coolant temperature sensor is the
problem.
On my car the cooling fan would not come on until the gauge was almost
all the way up to the H. I found out in my case the coolant
temperature sensor was cracked. Replacing it also improved my gas
mileage since the old sensor was telling the computer the engine was
cooler than it actually was. The sensor tells the computer what the
temp of the coolant is, and the computer decides whether that
temperature is hot enough to turn the fan on or not. This is usually
3/4 way up the gauge, in my experience, or with the A/C on, as someone
else mentioned.

It is only about $10-$15 to replace. Just make sure if that's it, and
if you replace it, that you replace the coolant temperature sensor and
NOT the temperature sending unit for the gauge on the dash. They look
similar and are located in the same general area on the engine- below
the air intake.

Model confusion: the older model Saturns, at least, have no model
designation anywhere on the car that I know of. You kind of have to
know what you have. In the early 90s, if you had black bumpers and had
no reflector between the taillights, you had the single overhead cam,
less expensive version, usually designated S_1. If you had body color
bumpers and had the reflector between the taillights, you had the dual
overhead cam motor and had the more expensive version, designated S_2.
If it was a coupe, the more expensive version had hidden headlamps,
while the less expensive version had normal headlmps.

I did not know in the early years that the coupe only came in one
version.

Actually I think the sedan came in 3 versions for a while- SL1, SL2,
but also just "SL". This third option was very basic, I think, and was
only available with the single overhead cam motor and was a stick
shift.

 

You are correct!

 

I have found it is not safe to rely on the computer to
turn on the cooling fan. The computer forgot once and
I overheated and broke a hose. Since then I installed a backup thermostat
switch from JC Whitney. It is a mechanical type that has a sensor that
sticks in the fins of the radiator and you can adjust the temperature of
when it switches. I put this switch accross the relay contacts that normally
turn on the fan. I little more peace of mind!

Fred
94 SC2

 

I have found it is not safe to rely on the computer to

Uh, what? I've got a 94 SC2 with 142k on it that I bought new, that has
been driven for eleven years in temperatures from -30 to 110 degrees, both
on and off the race track. I've never had a problem with cooling when
allowing the factory PCM to control the fan like it was designed to do.

I also have a 92 SC which is a dedicated race car which often shows
frightening temps on a couple of Autometer oil and coolant temp gauges. I
also let the stock computer control its fan and I've never had a problem.

Computer forgot once? I like that, I'm gonna use it at work.

Thermostat, coolant, hose integrity, clamps, fan relay, air dam, and a
handful of sensors - there's a lot of stuff other than the PCM that needs to
work right to allow the fan to work properly and the allow the cooling
system to do its job. I hope you checked all of them prior to installing an
add-on thermostat/fan controller. Otherwise that solution may have just
covered up a different problem.

Lane [ lane (at) evilplastic.com ]
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