: 94 SLS rad fan switching sensor

Rob Benham
11-17-04, 01:06 AM
I have read the hand book and other references to the "fans" --one on for a / c and two for eng overtemp. I had always assumed that this meant the main rad fans, but now I'm not sure.

I have never seen one rad fan on, just two when i select a./c this results in me using the a / c more -- just to keep the engine temp down in traffic. Can anyone advise where the water temp sensor is that turns on the fans, its resistance or switching readings and wether I should see one rad fan running alone. Thanks RB

11-17-04, 01:17 AM
I think the fans work in tandem. They come on (low speed) when the coolant temp reaches 225f and high speed at about 230f. They are always on when A/C is selected. Sounds like your system is working as intended. No need to use the A/C to run the fans. Just let it do it's thing.

11-17-04, 01:42 AM
That is correct. IIRC, the fans get hooked up in series (through relays) for low speed and in paralled for high speed. Both fans will always spin when they are on (in any speed).


Rob Benham
11-17-04, 11:56 PM
Thanks. When I first joined this forum, I told of buying this car from a young lady that it transpired was probably a superb sales person. The fans had been hot wired to come on with the ignition -- but still the temp was creeping up in the Texas heat. I replaced the stat and the belt and all was well, so I rewired the relays using only a bit of detective work as to the circuit.

Now that I know that there is a two stage process, my guess is that I probably do not have it hacked unless the A/C always = fans full on. And the two stage is only relevant to the water temp.

Due to the age of this vehicle I'm a little wary of letting the temp go much past 210... perhaps I should give it a test. What I thought was that I would test it by the sensor which is obviously two stage or computed -- but do you think that i can cause any harm by letting go to the hi 220's ??


11-18-04, 01:01 AM
I know that AC plays a role in controlling the fans. But I don't have the manuals handy, so I'm not sure if AC turns them on full speed. But the temperature of cooland is certainly responsible for both the lo and hi fan speed. If you search this forum, you can find the exact temperatures for both modes.

If you go iinto diagnostic mode, you can override the fan control, so you can actually make them go into lo and hi modes. That would verify if you rewired them correctly.
Again, I don't have the specific procedure handy...

My 93 Eldo with over 110k miles on it goes from about 194-226 for temperature range.
That is quite normal (Bbobynski says so...) :D


11-18-04, 05:46 AM
The fans are designed to come on when the temp reaches the 223-225 mark

Rob Benham
11-19-04, 12:35 AM
Thanks again for temps and diags...great idea. I was just about to print out the entire code list while visiting my son, but his printer quit at that moment, and I'm darned if I can find it again now I'm back home. Any links would be welcome. RB