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Fan doesn’t turn on until 250-255

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Fan doesn’t turn on until 250-255

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Old 08-20-2018, 11:07 AM
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Fan doesn’t turn on until 250-255

The cooling fan doesn’t turn on until 250-255 degrees. Replaced two new temp sensors. Same issue.

The fan fan turns on with the a/c on, but it gets mighty toasty if the ac isn’t on.

ideas?
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Old 08-20-2018, 11:52 PM
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Re: Fan doesn’t turn on until 250-255

Year of car? Engine? Radiator full? Air in the system can give incorrect coolant temp readings.
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Old 08-21-2018, 03:56 AM
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Re: Fan doesn’t turn on until 250-255

95 Camaro 3.4

No air pockets, newer radiator. Overflow bottle replaced.160 Thermostat.

With the ac on, its runs nice and cool...1/4 if the way up the gauge. Ac off....the fan doesn’t turn on until just barely before the red.

It’s been doing for awhile. Just fed up with it. Seeing if anyone as any ideas.


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Old 08-28-2018, 01:14 PM
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Re: Fan doesn’t turn on until 250-255

And the coolant temp sensor you replaced is the one under the intake plenum, toward front of engine. two wire connector with a yellow wire and a black wire?

The typical fan on programming is 236-degF. That is about the 3/4 mark on the gauge.

The 3.4L V6 has a single fan setup, correct? If the fan turns on when the A/C is turned on, all the fan circuitry has to be OK. Has to be a problem with the sensor circuit, or the dash gauge circuit.

Key on/engine off, take the connector off the 2-wire sensor. Measure the voltage between the two pins in the harness side of the connector. Should be 5 volts. Then with the connector still off the sensor, measure the resistance across the two pins on the sensor. Resistance should be close to the resistance shown in this writeup. Often best to test it with the engine cold, so you can estimate the coolant temp from the ambient air temp. Or pull the sensor, place in ice water for 32-degF reading, place in boiling water for 212-degF reading. When the page opens, scroll down for additional info for testing the sensor for the dash gauge.

4th Gen LT1 F-body Tech Articles

The above is a V8 writeup, but other than the location of the two sensors, it applies to the V6 engine.


You can download a free copy of the 1995 factory service manual here:

http://www.mediafire.com/?40mfgeoe4ctti

The 3.4L engine control system starts on .pdf page 2024. ECT codes are discussed starting on page 2063.


If all else fails, we can use the V6 version of Scan9495 software to data log the PCM, and see what temperature readings it s getting from the sensor.

https://www.firebirdnation.com/forum...for-34l-f-car/
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