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Working with a 2001 Oldsmobile Silhouette. Cooling fans ...
Sent to Car Experts March 15 07:04 AM

Working with a 2001 Oldsmobile Silhouette. Cooling fans will not run. Replaced engine control temperature sensor. Still will not come on. Unplugged sensor to check for change in resistance as vehicle was running and fans come on. Resistance dropped as engine heated up. Plugged sensor back in and fans turn off. This verifys that the relay circuit is working properly, and also checked that 5v is coming from the PCM to the sensor. Also, while running the heater, don''t get much warm air while stopped, but get warm air while driving. Could this be caused by the water pump or thermostat?

 

Optional Information:
2001 Oldsmobile Silhouette 3.4L

Already Tried:
Replaced engine control temperature sensor. Relays work because when I unplug the ECT sensor, fans come on.

Customer (name blocked for privacy)
Status:  Closed   Value: $9
Answer
March 15 9:35 AM (2 hours and 31 minutes and 6 seconds later)
         
REPLIEDCheck Mark
Hello Camaroman,you can have either a defective thermostat that is not letting the engine get hot enough to turn the fans on, or an air pocket, that will also not let the sensor get hot enough to turn the fans on ,and give you the heater problem. I would replace the thermostat and then bleed the cooling system.Try to bleed with the engine off,sometimes doing it with the engine on ,causes air to be sucked in. You may want to fill it with the sensor loose to see if you get coolant to flow there. Good luck,Jerry,

I will give an honest answer to the best of my knowledge. If my answer helps, please accept,if it saves you some money a bonus is appreciated.Thanks for using Just Answer, Jerry
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Roadside Jerry -- Auto Mechanic -- 100% Positive Feedback on 755 Car Accepts
Auto Mehanic 39 years,30 with the NYPD Fleet Service Division
Reply
March 15 2:27 PM (4 hours and 51 minutes and 49 seconds later)
         
Reply to Roadside Jerry's Post: The sensor is also the sending unit for the temperature gauge. I noticed what was happening with the fans because engine temperature was becoming quite elevated when at a stop, and would cool down while driving (air flow). The sensor is also working properly since as the engine heats up, the resistance across the sensor is dropping as well. It had dropped down to about 200 ohms which should correlate to around 200 degrees. As I had said previously, with the sensor disconnected, fans turn on. When I plug it back in at said temperature, fans immediately turn off.
Customer (name blocked for privacy)
Answer
March 15 2:55 PM (28 minutes and 25 seconds later)
         
ACCEPTEDCheck Mark

Hello Camaroman,I am sending the temperature / resistance value chart for the sensor on your car ,it may be slightly off. The fans don't generally turn on until the temperature gets closer to 235 degrees, although I couldn't find the spec for your car. A lazy thermostat can be causing your problem,I would replace it as a fist step.

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I will give an honest answer to the best of my knowledge. If my answer helps, please accept,if it saves you some money a bonus is appreciated.Thanks for using Just Answer, Jerry
Picture
Roadside Jerry -- Auto Mechanic -- 100% Positive Feedback on 755 Car Accepts
Auto Mehanic 39 years,30 with the NYPD Fleet Service Division
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