1998 Saturn SL2 Cooling Fan Not Coming On

SATURN
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RGREEN
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I have a 98 Saturn SL2 with 140k miles. The engine cooling fan does not come on in normal driving. It does work when the air conditioner is running. I have changed the radiator cap, replaced the sender and replaced the wiring clip on the sender. I checked the relay and it is operating correctly. The gauge in the car reads correctly. The car runs in a normal range when driven on the highway but will begin to heat up in traffic. Radiator fluid levels are ok.
I was told I might change the thermostat but I don't see how that would effect the fan operation as the engine comes up to normal tempature and hold there during normal driving.

Any ideas of what else to check.

Thanks
Feb 14, 2006 at 7:20 AM
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2CARPRO JACK
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cooling fan switch, next to the coolant sensor
Feb 14, 2006 at 9:30 AM
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PEPPERMRJ
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[quote:7e50121e4a="rgreen"]I have a 98 Saturn SL2 with 140k miles. The engine cooling fan does not come on in normal driving. It does work when the air conditioner is running. I have changed the radiator cap, replaced the sender and replaced the wiring clip on the sender. I checked the relay and it is operating correctly. The gage in the car reads correctly. The car runs in a normal range when driven on the highway but will begin to heat up in traffic. Radiator fluid levels are ok.
I was told I might change the thermostat but I don't see how that would effect the fan operation as the engine comes up to normal tempature and hold there during normal driving.

Any ideas of what else to check.

Thanks[/quote:7e50121e4a]

You might be chasing a ghost here. We know the cooling fan and relay work if it is coming on with the AC. You said you replaced the sender. I assume you mean the Coolant temperature sender (ects) and it's connector. Good move. The older sensors were made with a composite/plastic tip that would crack after a while and leak coolant onto the connection. Did you replace it with the updated brass tipped design from saturn. The jury is still out on the reliability of aftermarket ects.

The gauges on the saturns aren't exactly precise. The one on my 96 SC2 stays around 3/8ths to a half most times. My fan kicks in at about the 3/4 piont and runs untill the gauge goes back to 5/8ths.

Your gauge might show it slightly different. The key is that it stays consistent. Meaning that the fan comes on and goes off at the same spot on [b:7e50121e4a]your [/b:7e50121e4a]gauge.

I thought my fan was not coming on also. I was just impatient. It took almost 20 minutes from a cold start on an 85 degree day for it to engage at the spot on the gauge that I previously mentioned. Give it a try. I would not worry even if it does not come on until the gauge hits 7/8ths.

One way to tell if a thermostat is hanging open is by the output of the cars heater. If you are getting good heat in the same amount of time from start up the thermostat should be functioning properly. If the heat is slow coming on or does not get hot enough that would mean that the engine is running too cool.

96 and up saturns have only one ects that controls the gauge and sends signals to the PCM (computer) that turns the cooling fan on.

95 and older had two sensors. One controling the gauge and the other sending the signal to the PCM. I believe that is what Jack is refering to.

If the fan still does not come on double check the wiring. I i remeber correctly the PCM sends a 5 volt signal to the ects and depending on temperature the sensor sends back 5 volts or less.

Good luck and let us know. :)
Feb 14, 2006 at 11:29 PM

Suggested Repair

On this 1996-and-up Saturn, one coolant temperature sensor feeds the gauge and the PCM that commands the fan. Confirm it is the updated brass-tipped sensor, allow a higher consistent gauge reading before expecting the fan, use heater output to check the thermostat, and recheck the sensor wiring and 5-volt reference if the fan still does not engage.

Conversation Summary

The owner of a 1998 Saturn SL2 says the engine cooling fan does not come on in normal driving or traffic, although it runs with the air conditioner on. The radiator cap, temperature sender, sender connector, and relay have been checked or replaced, and coolant level and highway temperature are normal. Experts explain that 1996-and-up models use one coolant temperature sensor for the gauge and fan control, that the fan may engage only after a long idle at a higher gauge reading, and that heater performance can indicate thermostat function. They also recommend verifying an updated brass-tipped sensor and rechecking the sensor wiring and signal.

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