Coolant fan on 1989 Cady

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  #1  
Old 06-04-05, 01:26 PM
rgj
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Coolant fan on 1989 Cady

I have a 1989 Cadillac Seville. The "Coolant Fan" warning message keeps showing up on the console display. The fan does not turn at any time, even when the coolant temperature is above 200. I have removed the electrical connection to the fan and connected the fan directly to the battery. The fan works fine. I have also connected a volt meter to the electrical power plug which plugs into the fan. With the fan dissconnected from the plug and the ingnition on I get 12 volts. But if I connect the fan I get 0 volts. What would stop the fan from getting power ? What do I check next ?

The fan does work if I turn on the air conditioing.

Bob
 

Last edited by rgj; 06-04-05 at 01:50 PM.
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  #2  
Old 06-04-05, 06:59 PM
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Check the engine temperature sensor. Start by just unplugging the sensor when the engine is hot and see if the fan starts to run. If so, replace the sensor. You probably have multiple engine coolent sensors, so be sure to check each until you find the problem.
 
  #3  
Old 06-04-05, 07:15 PM
rgj
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Additional info

The temperature readout on the console does show the correct temperature. So that sensor is OK. So if it is a sensor problem there must be a separate sensor for the fan. Does anyone know where that sensor is located ?

Thanks
Bob
 
  #4  
Old 06-05-05, 08:56 AM
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Do you have two cooling fans? If so, are both working when you apply 12V? The wiring diagram from autozone shows you have 2 fans, along with a fan control module, a body computer module, and the ecm which all are factors in the fan operation. Figure 84 at http://www.autozone.com/servlet/UiBr...3d8015922a.jsp

If not a temp sensor or one of two fans are not working, there could be a problem with one of the modules, hard to say how these work. My guess is that the ecm is detecting a short or too much current draw or a problem with a module, thus cutting off power to the fan, but that is only a guess. Look for another fan, apply 12V again and see it both fans are working, if you see 2 fans, and also check both fans with the A/C on then post back.
 

Last edited by jeff67; 06-05-05 at 09:11 AM.
  #5  
Old 06-05-05, 12:46 PM
rgj
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Yes 2 fan

There are 2 fans and both are showing the same problems. Neither comes on when the car get hot. Both come on when the air conditioning is on. Both work if 12V is applied.

I have not checked the temperature sensor. If I locate it I will check it out.

bob
 
  #6  
Old 06-05-05, 05:37 PM
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I don't know where the sensor is but could definitely be the problem. Hope you found it. You might also want to check the coolant level, thinking it could be too low to trigger the sensor.
 
  #7  
Old 06-05-05, 06:16 PM
rgj
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Temperature sensor

I can not find the temperature sensor. I have looked on the radiator and on the block but I could not find it. If anyone knows where it is located please let me know.

As I said before the engine temperature does show up correctly on the engine data on the consol. So if the sensor that reads the temperature for the consol is the same as the one for the fan then it appears to be working. But I can not find that sensor either.

bob
 
  #8  
Old 06-05-05, 07:40 PM
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It is likely that the sensor for the gauge is a different sensor than the one used to control the fan. Don't ask why, it just happens. Look for anything screwed into the engines water jacet, manifold, etc.

When you find one, even just guessing, uplug the wire(s) to it while the engine is hot. If your lucky, your fan will start and you've found the problem. However, this is not always true about the fan coming on,, depends on the circuit design.
 
  #9  
Old 06-06-05, 10:00 AM
rgj
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Still can not find it

I have looked all over the engine and cooling system and I can not find the sensor. If anyone knows where it is hiding please let me know.

Thanks
bob
 
  #10  
Old 06-06-05, 10:22 AM
rgj
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Found one however

I found a temperature sensor hiding near the distributor under the air cleaner ducting. With the key in the on position I unpluged it. The fans started up. Now here is the weird part. The sensor is the one used for the readout on the consol display. The consol display shows the correct tempersture when the sensor is connected. When I run the engne the consol display shows the temperature rising from anbient temperature on up. When I disconnect the sensor the consol displays a temperature of 195. What is going on here ? Since the consol display is reading the correct temperature from this sensor it must be working OK. But since the fans go on when I disconect it the sensor must be bad. What am I missing ?

HELP


bob
 
  #11  
Old 06-06-05, 10:41 AM
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You have assumed that you know the circuit design of the sensor. Sensor design varies widely.
 
  #12  
Old 06-06-05, 11:18 AM
rgj
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Now what

What should I do next ?

thanks
bob
 
  #13  
Old 06-06-05, 04:43 PM
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Take the sensor with you to the auto parts to be sure the replacement part is the correct one. Buy it, install it.
 
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