2002 Grand prix cooling fans

[beltfeed]

Hi folks, new guy here with one on going headache. I have a 2002 Grand Prix v6 (3.8) non- supercharged with a cooling fan(s) issue. The cooling fans will not run at all unless the AC is turned on which is a overide mode that turns the fans on. They both used to come on around the 170 degree mark but now you can let the temp get all the way 220 degrees plus and the fans will not come on. If you turn the AC on they both come on properly. I have changed all three fan relays, coolant temp sensor (3 wire type) and changed the ECM out with another from another 2002 Grand Prix v6 (3.8) non- supercharged. The code #'s on the ECM match perfect and the car runs and drives fine with the different ECM but no fans. I am a pretty good wrench but this problem just doesn't want to go away. I know I could piggyback another fan controller system in that would bypass the factory wiring but I would rather not. I don't like to butcher things if I don't have to. Thanks for the help on this one, Pete

[BNaylor]

Welcome to AF.

So your cooling fans were turning on at 170 degrees F without A/C operation? That doesn't sound right. The cooling fans are programmed to turn on at 223 degrees F in low speed and 230 degrees F in high speed. The cooling fans are supposed to turn on with the A/C on as long the refrigerant pressure is greater than 190 psi and that is classified as normal operation not an override mode.

Is the 220 degrees at idle or what condition(s)? It sounds like you have other issues causing the higher than normal engine operating temperature. With engine off unplug the ECT (engine coolant temperature sensor). Then start engine and see if both fans turn on in high speed mode within approximately 5 seconds which is a failsafe mode.


BTW - Mine turn on at 180 degrees in low speed regardless of A/C operation but I have a re-programmed PCM module (Intense).

[beltfeed]

Thanks for the reply and welcoming BNaylor. I bought this new for my wife in 2002. Up until a month ago or so this car had never ran a engine temp over probably 180 degrees even if it was 95 degrees out. I think I'm going to change out the coolant tonight and see if that helps to maintain a lower engine temp.

So your cooling fans were turning on at 170 degrees F without A/C operation? That doesn't sound right. The cooling fans are programmed to turn on at 223 degrees F in low speed and 230 degrees F in high speed. The cooling fans are supposed to turn on with the A/C on as long the refrigerant pressure is greater than 190 psi and that is classified as normal operation not an override mode.

Is the 220 degrees at idle or what condition(s)?

get to 220 plus degrees it will require a fast idle speed of about 1500 RPM for fifteen minutes on an 80 degree day. Driving in stop and go will get the temp up to 200-210 on a 80 degree day.

It sounds like you have other issues causing the higher than normal engine operating temperature. With engine off unplug the ECT (engine coolant temperature sensor). Then start engine and see if both fans turn on in high speed mode within approximately 5 seconds which is a failsafe mode.

Did this test and both fans did come on after a few seconds in low speed and then they switched up to high speed in another five seconds.


BTW - Mine turn on at 180 degrees in low speed regardless of A/C operation but I have a re-programmed PCM module (Intense).[/quote]