Radiator fan question

RuSsMaN

My step daughter is getting her first car for her birthday, it's a 94 Saturn SL2 Twin Cam. It's a solid car, but I've got a fan issue.

It's not kicking on at all while driving or during idle. It starts to heat up during idle, and cools back down once you get going again. The 30 amp fuse under the hood is good, and the relay is fine also (I swapped it with fog lamp relay - identical, and the fog lights work fine).

The fan DOES work if you turn the a/c on, so what am I looking at here for the next step? There is obviously a circuit that kicks it on automatically when you turn the a/c on (which makes sense), but is there a relay or switch that should be opening due to temperature alone, but isn't? Both the top and bottom hoses are warm (water is circulating), the radiator is full, and no steam out of the tailpipe or water in the oil.

Cheers,
Russ

Toolfan66

Russ,

For me it has always been the relay for the most part, a couple of times it turned out to be a bad fan motor..

Jstas

Thermostat/temp sensor is bad. Some cars have two. They have a coolant temp sensor and one for the fan, especially if it's electric. That's my first thought.

Lotsa AC systems have a bypass for when you turn on the A/C. If there is no air flow over the A/C parts, they don't transfer heat and cool the car. So the A/C button bypasses all the other switches and relays and turns the fan on for the entire time the A/C is on.

I gotta check ALLDATA when I get home to make sure but I should be able to find the diagnostic procedure and part numbers you need.

RuSsMaN

Sweet.

sucks2beme

I've had that problem , too. Fan is good if the AC kicks it on.
The real question is what the path is for the relay turn on.
I'd say the relay is computer controlled, and the temp sensor that
signals the computer for the fan is kaput. But as always, docs tell
the story. If JSTAS doesn't find the answer, time to drop $25 on
the service book. On a 1994, there's going to be a lot of other
surprizes coming your way, so you just as well go for it.
There's always the brute force solution: jump the relay control
lead to leave it on all the time. It's Dallas, it certainly is going to be
on most of the time, anyway.

MillerLiteScott

Prolly temp sensor or check for a bad ground for the fan motor or in the fan relay circuit.

Vette C6.r

Please just check the rad. fan switch before all of this.

It is usually in the rad.

The fact that the fan comes on when the A/C is in use says that all is well with the motor and relay.

Please keep in mind that newer cars tend to run a bit hotter than older cars due to ECU controls of a ton of electrical inputs to the computer. The hotter they run usually the less emissions and quicker warm up times. The quicker the engine can lean out the better. At start up fuel is dumped in the engine until it warms up.

AudioGenics

http://www.youtube.com/watch?v=cucm7QGlsYs&feature=fvw

perhaps this may help

RuSsMaN

Great video. I like the fact it's an old timer doing it too.

hoosier21

does the light come on when you open glove box? I would check that first.

RuSsMaN

I'll check and see. Is there supposed to be gloves in there? Should I put some in if there isn't any?

Jstas

OK dude, you have two sensors for temperature in that pig.

One is the temp sensor for the temp gauge.

The other one is the Engine Coolant Temperature (ECT) Sensor.

The engine cooling fan will be turned "ON" or "OFF" by the PCM dependent upon engine coolant temperature, vehicle speed or A/C "ON" request. Under high ambient conditions, the fan may run up to four minutes with the key "OFF". If the PCM should become disabled a ground for the fan control relay will be automatically provided.

If the fan comes on at all, the relay is working and the motor is working. If the fan comes on when the A/C is on but not when it's hot, the PCM is working. Therefore a sensor is likely bad. Since you gauge works and you can see it's hot, that sensor is working. Since you can see it's hot but the fan is not on, then the ECT Sensor is likely not working. You will know that for sure if the car runs rough and idles high alot. It means that the ECT is not returning a value in spec and the PCM is trying to compensate by heating the whole shebang up. Therefore, the best option right now is that ECT Sensor.

BTW, PCM = Powertrain Control Module.

The only switches, relays and sensors in your cooling system are:

Temp sensor - Temp gauge
Temp sensor - engine coolant temp (PCM)
Fan relay
Coolant level switch - in overflow canister

Judging by what you are describing, the issue is caused by your ECT Sensor.

This where it's located:

http://www.polkaudio.com/forums/attachment.php?attachmentid=53687&stc=1&d=1291424581

That shot should be attached to this post too.

You will need this sensor:

http://www.rockauto.com/catalog/moreinfo.php?pk=942190



Part Numbers:
- O.E.#: 21025106
- Airtex/Wells#: 5S1124

You don't have to get it from Rock Auto but you should be able to get someone at a parts store to cross reference it.

Also, this fixes a TSB (Technical Service Bulletin) which is related to your current problem. The part number I referenced above is the "fixed" part so it'll kill two birds with one stone.


You'll need:
- A socket wrench
- A deep well socked to fit the sensor
- Loctite #242 (I think it's the red stuff, number is on the bottle, might be blue since it's being used as a thread sealant)

To repair, it's about the same as a spark plug. Do this when it's cold so all the coolant is down in the bottom of the block and you get minimal spillage. A deep well socket should work just fine. Unplug the electrical connector. Should be a simple squeeze and tug. If it's being a pain, needle nose pliers will convince it that moving is in it's best interests. Unscrew it with the ratchet, use a clean bucket to catch what will come out. Apply Loctite to the threads. Don't go overboard but don't necessarily be stingy either. Then screw the new sensor in. Snug it down with the wrench. Spec is 71 INCH pounds, not foot pounds, INCH pounds. Means don't gorilla grip it like Buddy Whackit and crank down on it. Tighten it easily until it stops and then give it a 1/4 turn more, that's it. Plug the sensor back in and start the car. Let it warm up. If the sensor leaks, snug it down a bit more, just enough so it stops weeping.

Did the fan come on? If so, YAY! If not, gimmie a call and we'll go from there.

Oh and that coolant that may or may not have come out in to the bucket? Yeah, once the car heats up and the thermostat opens, the coolant level in the overflow should drop. Dump the coolant in the bucket back in to the overflow. It should mix back in. If the coolant remains high, there is likely air in the system. Grab the top hose of the radiator and squeeze. It'll help get the air your repair let in out. It's called "burping the system". Yes, just like a baby.

Jstas

Yeah, the video is good but, don't use tape. The block gets hot and tape doesn't necessarily stand up to the heat. Use the Loctite. It's designed for that environment.

Yeah, and the Loctite 242 is the blue stuff.

http://www.amazon.com/Loctite-Threadlocker-Medium-Strength-color/dp/B0015PI75E

RuSsMaN

Awesome, I'm betting that's the problemo.

What I don't get, is looking at that thing, it looks like a brass plug? Are there no moving parts? Is it just a thermometer in the kazoo hooked up to electronics?

AudioGenics

technically it is called Temperature Coefficient of Resistance of Brass

the brass alloy sensor provides a resistance that the compooter can monitor
and if it is not within specification it goes kaput.

by the way what is the mileage of the Ringed Planet one.

RuSsMaN

It's a 94 with 173K. It could use more hp for me, but it handles like it's on rails. I drive a GMC Suburban, so this feels like a street legal go kart to me.

Cheers,
Russ

Jstas

Ah, Texas, the land that rust has forsaken!

RuSsMaN

The only salt around here is on the rim of a margarita.

WilliamM2

Plastic doesn't rust much anyways.

RuSsMaN

That's what I was just thinking.

Joe08867

Jstas wrote: »

Thermostat/temp sensor is bad. Some cars have two. They have a coolant temp sensor and one for the fan, especially if it's electric. That's my first thought.

Lotsa AC systems have a bypass for when you turn on the A/C. If there is no air flow over the A/C parts, they don't transfer heat and cool the car. So the A/C button bypasses all the other switches and relays and turns the fan on for the entire time the A/C is on.

I gotta check ALLDATA when I get home to make sure but I should be able to find the diagnostic procedure and part numbers you need.

Had the same issue on my VW golf. Worked with AC on but not other wise. It was definitely the sensor on my car. Working great ever since.