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View Full Version : 92 3.3 overheating - bad fan or sensor?



jcranfill
03-08-2008, 05:53 PM
Not sure how long this has been going on, as it's been a cold winter here. Additionally, I normally only drive the 92 Ciera about 2 miles each way to work. It hardly ever gets up to operating temp, even in the summer, unless I go out to lunch (and dont car pool) or run a random errand. Every now and then (about once per week) I'll let it sit and idle up to operating temp, then shut it down and go inside.

Here's the problem - Left work last night, decided to go about 5 miles out of my way to hit up a drive through. While sitting in the drive through, the temp started creeping up. and up and up, till the temp light came on. Took about 5 minutes. As soon as it came on, I exited the line and pulled into a parking space. Couldnt hear any boiling, so I shut it down. Immediately it started to boil over into the overflow. I started it back up, and pulled out onto the road, which is about .5 mile down hill stretch. I let it idle as I coasted down, and the guauge started to drop.

So now Ive been poking around trying to figure it out, and here's what I know:
The car is full of proper antifreeze mixture.
No leaks.
Oil/tranny fluid are still just oil and tranny fluid.
Antifreeze is still just antifreeze.
When the guage gets up to around 190ish, the thermostat opens and the gauge drops back down to where it always has, as long as Ive owned the car.
As long as I'm moving, even at parking lot speeds, it doesn't get over normal temp.
As soon as I sit and idle for more than 3 or so minutes (as long as the car is already at operating temp) it starts to creep up.
When the A/C is on, the electric radiator fan is not spinning.
When it starts to over heat, the fan is not spinning.
I can take one finger, and spin the fan blade in either direction with little resistance.

Soooo....It's either a bad fan motor, or a faulty sensor that controls it. I was under the impression its ALWAYS supposed to run with the A/C on. Correct?

As a diagnostic step - should I cut the wire to the fan, and apply a 12v source to it to see if it spins? If so, its a sensor - if not, its new fan time? Am I off base?

notsoslimshady76
03-08-2008, 06:02 PM
I know this sounds dumb, but make sure the fan is plugged in. You'd be surprised how many times the plug hasn't been plugged in by shops lol.

Rather than cutting the fan wire, you can jumper the plug under your steering column (the OBD1 port) just like you'd be checking for engine codes. That will make your fan run, and you can figure out whether or not there is something wrong with your fan

jcranfill
03-08-2008, 06:05 PM
Oh ya, the paperclip trick...forgot about that, it IS supposed to run when jumpered. I'll go check that in a few minutes.

In the meantime, I forgot to mention I did check the plug - seemed tight and correct.

a1veedubber
03-08-2008, 06:12 PM
I dont have much to add but to say that you are correct, the fan IS supposed to run with the AC on. You are on the right track at least!

jcranfill
03-08-2008, 07:39 PM
K - the fan does NOT run when in the system is in diagnostic mode...

BTW, no bad codes...lol

Well, I guess a new fan is in order?

notsoslimshady76
03-08-2008, 08:19 PM
I personally would just grab one in the Junkyard. The fans don't go bad too often. If that isn't an option, just hang onto the receipt in case that doesn't fix the problem!

CieraSL92
03-08-2008, 08:31 PM
Rule out the sensor, btw. There are two coolant temp sensors, one for guage, one for the ECM. The ECM uses its own sensor to control fan operation. If the engine runs okay, then the coolant temp sensor for the ECM is fine.. If you have a test light, you can connect its wires to the harness that plugs into the fan motor. Ground the diagnostic terminal with the ignition on and the test light should come on. If it does, its a bad fan motor.

I had the same problem, except moving the wire around actually made the fan come on. I spliced in a new harness.

jcranfill
03-08-2008, 08:34 PM
K - so shouldnt be the sensor - that leaves the switch and the fan motor...One I can test with a light, the other I can jumper to the battery to see if it moves. Not as bad as I thought. It'll be tomorrow before I can get the hood up again, but I'll report back. Thanks guys!

CieraSL92
03-08-2008, 08:36 PM
Yeah, you can jump it from the battery. There is also a relay, located behind the headlight in a block. Don't remember which one it is, but I think mine was the third one from the left. (on my 92 Ciera)

LordDurock
03-09-2008, 04:51 AM
i know this sounds silly check the ground.....................(i forgot to hook my fan ground up on time ;))

after that try jumpinghte fan motor from battry to motor.

after that its sentor.

CieraSL92
03-09-2008, 10:44 PM
Durock, no dedicated fan sensor on his engine. We have a coolant temp sensor for the ECM, which decides when to turn the ECM via the relay. If the temp sensor was bad, the ecm would also have screwed up Air/fuel balance since it also uses coolant temp to adjust.

jcranfill
03-10-2008, 12:30 AM
$25 and one fan motor later, all is well. It was indeed the fan motor. Stuck a multimeter into the socket from the engine, jumpered the 1/2 again, and I got 12.4 volts. Hotwired the fan to the battery, and nothing!

Took about 20 minutes total not included drive time to AutoZone. Good thing was, I could still drive out there with the entire fan assembly in the backseat - reassembled it in the parking lot.

Thanks for the input guys!

MR2Di4
03-12-2008, 07:19 AM
At least you got it working normally again.

I was about to suggest checking the fan relay as your Ciera is probably like mine and has a fan relay under the hood on the right side of the front support. I had a similar problem and it turned out to be the relay instead of a fan or sensor...