93 SSEI Radiator fan ONLY WORKS with AC on

[93 White SSEI]

Both fans come on when the AC is on.
No fans come on any other time, no matter how hot the Vehicle gets.

Where should I start ? Relay? Any information would be greatly appreciated.

Thank You.

[myfirstbonnie]

How high on the temp gauge has it gone? Do you have access to a scanner?

[xvr843]

i have the same problem with my 96, i already change the temp sensor and change all fuses as well. only works when the ac is on

[myfirstbonnie]

Fans do not come on until 225 degrees iirc. The temp has to get pretty high on the gauge. The gauges are not very specific on the temps.

Are you having an overheating issue?

[J Wikoff]

Swap your low and high speed fan relays and see if the condition changes. Also check all the fan fuses on the maxifuse relay center.

[myfirstbonnie]

I am just trying to determine if there is even a problem. He has not said if there is an overheating issue or even how high the temps get.

[xvr843]

Had a shop to straight wire my fan because it use to over heat. Cooling fan never worked. Its fine now... And all fuses are new

[myfirstbonnie]

The OP has notmentioned his issue yet. As for yours, I suggest removing whatever was done to straight wire them and do some troubleshooting. It will be hard to do with them bypassing everything else.

[1oldman]

If you get a code scanner to use, some can actually read the water temperature. If you are able to get one, get the temp readings from the code scanner. IIRC low speed fan runs at 212F and high speed fan starts at 224F. If the engine never gets that warm, the fans will not run. If you get a code scanner that can give commands back to the PCM, you can turn the fans on and off with it to see if there really is a problem.

Some read the temp only in Celsius. To convert to F multiply by the Celsius temp by 1.8 to get the temp in Fahrenheit. - BC

edit - the 1.8 is good only if the temp is 0C or 32F or warmer. - BC

[93 White SSEI]

It routinely will get to the line, or slightly over the line that I believe to be 225 ( solid white line after the 200 line )
Only while stopped, while driving it is stuck at 197*, with air on no matter how long I sit it is at 197* (* slightly under the 200 line)

It never spins, slow fast or otherwise unless the AC is on. Do you remember which relays to switch exactly, my chilton covers 85-05 and like 3 models so its pretty much useless lol.

I have never over heated per se, but id like to be at or under 200 at all times, namely because 225 can become huge problems quickly here in south florida where it is about 90 daily now....

Thanks for the help so far. I have no code scanner BUT the coolant temp sensor is NEW within 2k miles as I re did my LIM as precaution when putting in a reman SC

[01bonneSC]

Do you have a cooler thermostat installed? Wont do much with out a tune, but it helps.

[93 White SSEI]

I have a 180* Tstat, a NEW radiator ( which was a PITA bc everyone i got from the store wasnt right, i settled on one without the Low Coolant Sensor, but proper size tranny cooler fitting ) and of course new fluid.


Do I correctly remember a simple mod to wiring INSIDE the car that permitted CONSTANT fan operation? Maybe by the foot on drivers side ?? ( i would like to resolve the issue correctly but this remains an option )

[sandrock]

Set temp for the fan turn-on IIRC is around 212*, with turn off around 197*. Also remember that you have two temp sensors...one is strictly for the pcm (and fans, which the PCM controls) and one is strictly for the temp gage.

[93 White SSEI]

which sensor is threaded into the LIM and where is the other one located?

[sandrock]

Both are threaded into the lower. One will be beneath the TB, the other towards the firewall. I forgot which controls what though.

[Icebound]

I believe that the Temperature sensor driving the fans will have two wires: black, and yellow, and it is possible that the sensor for the Temp guage will be black and green or possible just a single wire green.

The guage sensor is a variable resistance with about 40 ohms at high temperature (250F or so), and 1300 ohms at low temperature (100F or so). The guage sensor may well have changed its calibration so that the guage may actually be reading high (or low) and no longer matches the sensor which sends to the PCM.

Your fuses have to be good if the fans run at all. It needs a good 10 amp fuse to power the fan relays, and a good 40 amp fuse to run the fans themselves.

It is strictly the PCM's call to start the fans. Both the AC signal and the coolant temperature info go to the pcm. So if the fans run on AC, then that part works. If the fans do not run on high temp, then it is the temp sensor or that part of the PCM.

Note that the PCM expects the coolant temperature to be 100C (212F) before it asks for the low speed fan, and 108C (226F) before it ask for the high speed fan. That is pretty high.

It is possible you don't really have a problem at all.

[Billha]

I had the same problem on my '93. If both fans turn on when the AC is on, but the coolant temp continues to rise when the AC is off because the fans don't turn on automatically, then most likely the low speed fan relay needs to be replaced. It's located in the relay center in the engine compartment. 2nd possibility would be the coolant temperature sensor. If you have access to a scan tool, then you can easily check whether or not the coolant temp sensor is working. If it's not caused by one of those 2 parts, then there could be a wiring problem, but that's the least likely possibility of the 3.

Both fans come on when the AC is on.
No fans come on any other time, no matter how hot the Vehicle gets.

Where should I start ? Relay? Any information would be greatly appreciated.

Thank You.

[93 White SSEI]

where can i find something/link that describes what each relay is for, my chilton doesn't.

Thanks Guys

[Billha]

The relays are in the box labeled "maxi fuse relay center". As you're facing the front of the car, the low speed fan relay is on the far right, and the high speed fan relay is to its left (2nd one from the right). For example, you can swap the horn relay (2nd from the left) with the low speed fan relay, and then see if the horn works. If it does, then the relay is working (but there's a chance that relay may have an intermittent contact problem)...or on the '93 you can swap another relay with the low speed fan relay and jumper pins A and B on the ECM connector and turn on the key to 'Ign' and check to see if the fans turn on; the fans turn on when the ignition is on and pins A and B are shorted for diagnostic mode.

Here's a link to the image of the relay center:
http://www.google.com/imgres?imgurl=htt ... CCoQ9QEwBA

[93 White SSEI]

THANKS FOR THE REPLY RELAY IMAGE, I have only one OPEN relay spot, but this will help. Anyone know which one I have in addition ??