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Old 07-14-2009, 12:56 AM   #1
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Default 97 SSE Cooling Fans Not Coming On

I am having a pboblem with the cooling fans in my 97 SSE not working. If I unplug the coolant sensor the fans will run and if i plug it back in they will run for a couple minutes but will go off and not come on again I know that it is going off when the temp goes down but if I let the temp go back up over 200 at idle the fans will not turn back on. I tried another coolant sensor but have the same problem, any ideas.
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Old 07-14-2009, 07:40 AM   #2
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The fans will cycle if working properly. You mention them cycling. But then they don't?

Please explain a little more.
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Old 07-14-2009, 07:33 PM   #3
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Default cooling fans

Thanks for replying. If I unplug the temp switch and plug it back in the fans will run until the car reaches the proper temp then the fans will shut down but will not come on again when the the temp goes back up. The fans will only come on if i unplug the temp senor and plug it back in. I tried a new temp sensor and it does the same thing. It is not really a problem unless i am in traffic and the car starts to heat up to around 210 it has not overheated but i am afraid of it happening.
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Old 07-15-2009, 08:56 AM   #4
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Ok..

The way the system works is the pcm monitors the temp via the sensor. The sensor has two outputs, one to the gauge and one to the pcm. The pcm grounds a relay to power the fans at low speed, it grounds another relay to power the fans at high speed.

By unplugging, I'm unsure what is being accomplished. The pcm should see no temp and default the fans to on high speed as a safety. Then it appears the pcm sees the temp and turns them off.

I've known our dash gauges lie badly at times. Do you have a way to get a scanner on it to see the temps the pcm see'*?
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Old 07-16-2009, 01:34 AM   #5
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No i do not have a scanner. I know on most vehicles when you turn on the a/c the fans will run but they do not come on when i turn the a/c on.
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Old 07-16-2009, 08:21 AM   #6
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Ok. let'* trace down the relays and look over the resistors.

The relays for the fans are on the firewall under the maxifuse cover.
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Old 07-16-2009, 10:28 AM   #7
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In the meantime u might also consider getting a cooler thermostat, like 180 degree. It'll cut down on some of that engine heat as well.
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Old 07-16-2009, 12:08 PM   #8
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I had similar problems and the guys here gave me the info I needed to track down my problems. I ended up changing the two relays and the temp sender for cheap insurance. Everything works fine now. With the A/C on I run an indicated 190ish and without the A/C it runs up to around 220 or so. I never would have knew what temp the fans turned on by themselves, didnt even think it could be as high as it is. I was used to using the A/C everyday (Florida) and when I stopped to using it to save some fuel around the same time the lower hose blew out and overheated the engine. Thats when I started to notice problems. Turns out the only problem was that I was uneducated. Hopefully your problem has a simple answer too.
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