Cooling fan Recalibration
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GM has designed the ecm to turn the fans on at aprox 228* . if you have a scan too hooked up, and watch the temp sensor on it, you will see that it turns on at 228* and off again at about 207*. they do this because of emissions. a warmer motor runs leaner with the factory PROM settings. i have a hypertech thermomaster chip in my car and would have thought that they would have changed that, but they didnt. it runs cooler going down the road because of my 160* thermostat , but if i sit, the temps are the same as before. i do know that the older cars had a fan switch that was actually the ground for the cooling fans, and you can buy a replacement to lower the temp the fan kicks on. but i do know that mine is controlled by the pcm when it turns it on
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From: Brewerton NY
You should be able to reprogram the PROM to change the fan temp. I had a new PROM made that turned my Trans Ams fans on at 200 instead of the stock 228. Made a HUGE difference. I could have gotten the grounding switch as mentioned earlier. But I was afraid that it would HURT performance by telling the comp that the car was hotter than it really was. Besides, the PROM was only $70 from SLP.
Jay
Jay
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From: Brewerton NY
Originally Posted by fuddyduddy121
Hey now we're on to something!
Jay
Then I'll do the 180 t-stat mod that is unless the chip in the '95s can't be flashed.
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Forget the reprogramming. Just set up a standalone system with a new temp sensor set to whatever point you want, and have that control a relay to operate the fans.
Probably do it for 30 bucks or so.
Probably do it for 30 bucks or so.
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From: Arkansas
Forget the reprogramming. Just set up a standalone system with a new temp sensor set to whatever point you want, and have that control a relay to operate the fans.
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From: Saginaw, MI
Originally Posted by parallelcircuits
Forget the reprogramming. Just set up a standalone system with a new temp sensor set to whatever point you want, and have that control a relay to operate the fans.
would just need to find the diagrams for the wiring of the fans and figur e how to get the relay to work... but still simple, and cheap.
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From: Central Maryland
i like the idea of having the computer tell the fans to come on earlier. I am also in the process of having a chip burned for me, and that is one of the settings that is being changed. I need it bad b/c i run hot all the time in DC traffic 
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LewR
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Nov 10, 2003 04:38 PM