Question about 1987 Buick Century

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Radiator fan runs when conneced to 12 volts.but won't run when I jump out engine coolant sensor. also sensor has 5 volts ref. also can jump relay and fan will run. what could be the problem?

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Change the sensor if wires ok, if same problem, change ecm

Posted on Sep 13, 2010

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Put in new coolant temp sensor - fan still does not go on? Have to run the blower fan to keep engine cool. Question is would the Thermostat? have any effect on the Radiator fan?

On some vehicles the coolant temp sensor is separate from the radiator fan switch - there are actually two sensors. We would need to know the manufacturer, year, make, and engine size to make better determination of the cause of your problem.

Mar 19, 2015 | Cars & Trucks

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I have a 2002 Chevy Malibu 3.1 and I'm looking for where the engine cooling fan sensors location. Can anybody help me?

Unlike many older vehicles, there isn't a separate coolant switch for the radiator fans. The engine coolant sensor that provides coolant temp to the PCM for control of the fuel/spark/timing is the same sensor used by the PCM to control activation of the radiator fan(s).
The PCM activates the fans by activating relay 12 in the underhood fuse block for low speed operation and relays 12, 14, and 15 for high speed operation. If the engine is running normally other than the fan, the problem is not going to be the coolant sensor. But, if you need to see for yourself, the coolant sensor is on the drivers side of the engine, below and just forward of the throttle body. See the picture for clarity.

Dec 06, 2013 | Cars & Trucks

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The cooling fan does not turn on when my 96 Chrysler Concorde when the engine gets hot...where should I look for the problem?

Somewhere around the flange of the engine cooling radiator is a thermostat that opens and closes a circuit for the fan, but first check the fuse box in the engine compartment and look for the engine fan relay fuse... Check it out first!

Dec 31, 2012 | Cars & Trucks

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1994 Chevy Cavalier fan won't come on

Sounds like the sensor is not reading the coolant temp, or the computer is not accepting the data from the sensor.
Its possible you have air in the cooling system, or you have a problem with the computer.

Aug 28, 2012 | 1994 Chevrolet Cavalier

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I have an 89 camaro the cooling fan will not work unless you unplug the temperature sensor or hotwire it. I have replaced the temp. sensor and fan relay. I have tested wires to sensor from the sensor to...


Unplug the coolant temperature sensor while the engine is running. This should cause the fans to turn on low then kick to high, IIRC.
Typically when the engine computer loses the signal from the coolant temp sensor, it just turns both fans on high so the engine will not overheat. Ultimately, the fan is controlled by the computer. When it receives a signal from the temp sensor that reads the appropriate temp, it turns the fan on. One easy option is to wire a switch to the cooling fan relay. Then you can turn it on and off when you need it. I would not recommend running the fan constantly. You will burn out the fan motor and you'll never get up to normal temp for your sensors.

Check for coolant level and bad motor.

However as far as the fans and "disconnecting them from the temp sensor"..... The fans DO NOT connect directly to the temp sensor. They connect to the PCM (computer). The PCM reads the coolant temp sensor, and determines when to turn on the fans. It also uses the coolant temperature to control several other functions, including the transition from "open loop" A/F ratio control to "closed loop" A/F ratio control. It uses the temp to set the idle speed on cold start. It uses the temp to determine the cold start fuel enrichment. If you run this way, your car will be hard to start, it will run excessively rich, wasting fuel, and possibly even damaging the engine by diluting the oil.

Please get back to us if you have further query or else please accept this "particular" solution.

Sep 18, 2011 | 1989 Chevrolet Camaro

2 Answers

Electric radiator fan wont turn on . but when fan is jumped with 12 volts fan works

heres a little test start vehicle turn a/c on high in the defrost position your fan should start if so than test hi low fan relay and replace coolant temp sender not sensor in some cases replace both thank u have a good day.

May 04, 2010 | 1999 Jeep Grand Cherokee

2 Answers

Electric fan does not run "radiator"- I connected fan to 12 volts and it spun, fuse is good, is there a sensor? and where would it be located?

theres a coolant fan sensor in intake, but i think the problem is the fan relay,its in the right front of engine compartment on relay block.the sensor is at rear of head on coolant outlet if its a 2.2 engine, if its a 3.3 engine then the sensor is under alternator.

Dec 07, 2009 | 1993 Oldsmobile Cutlass Ciera

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2001 Jeep Cherokee Laredo- electrical fan

Have you tested the fan, use a set of clip leads and supply 12 volts of battery power to the fan to see if it runs, another test is to disconnect the engine coolant temp fan switch, this sends the system into default and the fan will run.

Oct 17, 2008 | 2001 Jeep Grand Cherokee

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