Cooling fan Recalibration - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 08-09-2003, 09:19 AM   #11
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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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Old 08-12-2003, 12:00 AM   #12
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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
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Old 08-12-2003, 12:05 AM   #13
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Hey now we're on to something!
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Old 08-12-2003, 12:14 AM   #14
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Quote:
Originally Posted by fuddyduddy121
Hey now we're on to something!
You can do it on OBD II cars with FLASH PROMS with a programmer like a Hypertech. It is very common. Unforthantely my T/A is non-flashable, and had to be burned.

Jay
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Old 08-12-2003, 12:22 AM   #15
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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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Old 08-12-2003, 12:30 AM   #16
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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.
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Old 08-12-2003, 02:10 AM   #17
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Quote:
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.
That is what I was thinking. My friend has a 85 Jeep that he has did some work on. He has a temp sensor in one of the fins of the radiator and a relay mounted to the inside fender well running the electric fan on the front of the radiator ( he had to take the fan that ran off the motor off for spacing purposes). The problem is he told me that he paid about $100 for the temp sensor and adjustable relay. That is pretty expensive.
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Old 08-12-2003, 04:18 AM   #18
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Quote:
Originally Posted by parallelcircuits
Quote:
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.
That is what I was thinking. My friend has a 85 Jeep that he has did some work on. He has a temp sensor in one of the fins of the radiator and a relay mounted to the inside fender well running the electric fan on the front of the radiator ( he had to take the fan that ran off the motor off for spacing purposes). The problem is he told me that he paid about $100 for the temp sensor and adjustable relay. That is pretty expensive.
couldnt you just borrow an old trick fromt he muscle car boys and set up a "heat" switch w/ a **** to control fan speed? and a simple relay or just a toggle for full on/full off of each fan... shouldnt be hard to do
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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Old 08-13-2003, 07:58 PM   #19
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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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