cooling fan doesnt turn on


Old 07-28-03, 04:41 PM
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Join Date: Jan 2003
Posts: 56
cooling fan doesnt turn on

93 lumina 3.1L with 2 fan works when ac is turned on, but primary one does not when sitting in traffic, gets into red zone and have to turn on ac to cool it down...relays fine and fuses good....switched leads on the fans and it works fine so i know both fans work....any hints on what to look for next?
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Old 07-28-03, 04:45 PM
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Join Date: Jan 2003
Location: Arkansas
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There should be a temp sender that turns on the fan when the engine gets warm/hot..COuld be you'rs has gone bad..
Old 07-28-03, 06:23 PM
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I agree. Check that and any fusible links inline.
Old 07-28-03, 10:30 PM
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Key on, Engine OFF. Jumper pins A&B on your diagnostic connector. The primary cooling fan should run. If it doesn't, check the 10A fuse in the Right Side Electrical Center. If the fuse is good, suspect the relay.

Your ECM controls the coolant fans based on input from the coolant temperature sensor. As far as I can tell from the wiring diagram, there is NOT a separate cooling fan thermostatic switch as on earlier models.

Below is the cooling fan circuit Description and Operation courtesy of Alldata.

Each Coolant Fan is turned on and off by a separate Coolant Fan Relay.

The Primary Coolant Fan Relay coil is grounded by the Engine Control Module (ECM) when vehicle speed is less than a speed determined by the ECM and the Engine coolant reaches 108C (227F) with A/C off or 106C (223F) with A/C on. The relay contacts close and voltage is applied through the Primary Coolant Fan Relay to the Primary Coolant Fan. The Primary Coolant Fan runs until the Ignition Switch is turned off, or Engine coolant temperature decreases to 104C (220F) with A/C off, or 102C (216F) with A/C on.

The Secondary Coolant Fan Relay coil is grounded by the ECM when the Engine coolant temperature reaches 118C (245F). The relay contacts close and voltage is applied to the Secondary Coolant Fan. The fan then runs at high speed and will continue to run at high speed with the Ignition in RUN until the Engine coolant temperature lowers to 114C (238F).
Old 07-29-03, 03:29 AM
Join Date: May 2001
Posts: 516
My friend has the same engine and problem as you, turned out he had a intake manifold leak that was keeping the fan from coming on.
Old 07-31-03, 06:55 PM
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Posts: 56

the intake manifold scared me....temperture fan sensor switch off the thermostat cured it....

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