94 SL2 cooling fan help

Someone I know has a 94 SL2 in which the cooling fan won't run. Here's what
we do know.


The fan runs when the jumper is inserted to retrieve computer codes. This
eliminates a bad fan motor or relay or connection to the computer. (but
should it run?)
Code 23 is displayed even after the sensor was changed.
Coolant temp sensor was changed also.
Temp gage reads fine but goes to HOT and fan doesn't run.

Where could the problem be. This isn't my car and I haven't looked at it.
I'm just going on what I've been told by the owner.

Chris

 

i had a similar issue with my 97 sl2...the fan wouldn't run when the
engine got hot, but when the a/c was on it would...but it didn't sound
right. turned out the motor was going and was spinning enough to make
noise. i could stick a tongue depressor size, flimsy stick into the
fan, and it wouldn't break it.

i took the motor off, and hooked it directly to a 12 battery (off the
car for safety) and the motor spun, but was very weak and easy to stop
by hand.

i would suggest getting a new motor.

if you want to test the relay, not for sure about the 94, but my 97's
a/c relay was the same as the fan, so i switched them.

one word of caution, the nut that holds the fan on is a reverse
nut...righty = loosey.

also, you may want to have the alternator tested at a local parts
shop, you may not be getting enough juice to run the fan and the rest
of the accessories.. it seems that with Saturn, when one component
breaks, the rest will follow.

 

If I'm reading this Chilton's right, code 23 says... IAT Circuit -
Temperature Out of Range Low

It also says... on 91-95 models, a coolant temp sender, as well as a
coolant temp sensor are used. Be careful not to confuse the single-wire
coolant temp sender used by the instrument cluster temp gauge with the
2-wire sensor used by the PCM.

 

Make sure that a) the right coolant temp sensor was changed (some models
have two), and b) the sensor connector is making proper contact (I've heard
of some cases of coolant leaking out of the sensor and corroding/damaging
the connector and harness).

 

When the motors start failing, they fail intermittently, or running weakly.
This is because the brushes get to the end of their travel (they wear out)
so that they aren't being pushed firmly against the commutator.

If it's normally run in a warm region and there are more than 60,000 miles
on the car, then you would be well served to replace the cooling fan motor.
It's by far the most common failure item when the fan doesn't run.

 

By far the most common? No way. Coolant temp sensors are far more common to
fail than a fan motor.

I would suspect a fautly CTS. Sometimes even new ones come no good. Check it
with an ohm meter.

 

Um, yeah. I wasn't writing down my entire thoughts.

If there is a known FAN problem (that is, you turn on the Air Conditioner
and the fan doesn't spin), then the motor is the most likely problem. Folks
tend not to realize that, even though the motor is sealed, it is a DC motor
WITH brushes, and those brushes wear out.

It sure would be nice if someone came up with either a brushless DC fan
motor (probably too expensive) or a regular DC motor that had easily
replaceable brushes (again, probably too expensive - as long as it lasts
through the warranty period you're OK).

 

It sure would be nice if someone came up with either a brushless DC fan

http://e-www.motorola.com/webapp/sps/site/overview.jsp?nodeId=03M0zpbnQXGM0zpqhv0V

http://www.railway-technology.com/contractors/hvac/honeywell_lmb/



I'm not sure how well these motors scale to the size of your typical
engine fan motor.

"Adapted for the first time for use in the rail industry, the brushless
motor is based on leading edge technology used in the civil aviation and
defence industries where before conventional motor commutation was
carried out using carbon brushes. Due to friction on the copper
collector the brushes wear out. Therefore, brushes and collectors need
frequent replacement. This requires disassembling the motor and
immobilising the train, tram or subway vehicle."

So maybe it would scale ... but is it cost effective, as you pointed out.

-rj
98SL2

 

Office copiers use lots of motors - none of them have brushes. Some of them
are very powerful. Our computer fans use brushless motors. Yes, it is
possible and practical but car makers sometimes take the cheap route.

Chris

 

I looked at the car today and it works now. I found the Intake Air Temp
sensor unplugged. I'm not sure why that would keep the fan from running but
it works now. Thanks for all your help.

Chris

 

Yeah, once they change over their manufacturing, it would be. The
trouble is the motor drive cost is STILL an issue. Then again, think of
all the great advantages to it - imagine a steering rack with the power
pump in the rack, motor submerged in oil. Can't do that with brushes.

Oh yes, more modern RR equipment uses 3 phase AC induction motors for
traction.

 

Imagine an electric power steering unit that doesn't need any oil. Oh, wait,
my ION has one. Never mind.