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Cooling fans don't run

 
Old 07-11-2019, 11:48 PM
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Went
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Default Cooling fans don't run

My 30ish year old car (1989) is at it again. The cooling fans do not run except when I jumper A&B on the OBD1 connector. Then they howl away. They do not start when the AC turns on. My fuses are all good...checked them all just for grins. I know the dash gauge is not to be trusted to be true but it read 242 before I got to my intended destination. Got jammed up in some heavy traffic. I am taking it to a shop...just don't have the time right now. Short handed at work and taking care of elderly parents doesn't leave car time.

But I am curious as to what the problem might be. The rest of the cooling system is pretty new. Water pump, thermostat, all hoses, Dewitt's radiator.

Thanks, Went

Last edited by Went; 07-11-2019 at 11:48 PM.
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Old 07-13-2019, 03:43 PM
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Though the ECM doesn't call for fan on till near the >200 deg F setpoint, I think it should come on with the A/C on.

Let us know what the shop finds as the issue.
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Old 07-13-2019, 05:53 PM
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Went
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The fans do not turn on with the AC so I think there might be a couple things going on. The car goes in the shop Monday morning.

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Old 07-18-2019, 10:03 AM
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The fan start problem turned out to be a failed temp sensor. Also, when the fans ran, the mechanic heard a rustling sound. I had a small leaf collection up in front of the radiator. It had been since last summer since I'd last cleaned that area of debris. He pulled it apart on top and pulled out the leaves. My HVAC control panel needs repair. It turns out that is the reason the fans wouldn't turn on with the AC. Couldn't turn down the temp low enough I guess to make the system kick on? Anyway I have functioning cooling fans now.

I'd like to setup a manual switch to have control of the front fan when I am stuck in traffic for extended periods and don't want to run the AC. Is there any problem concerning the cars computer running the fan manually? How best to wire this up?

Thanks again, Went
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Old 07-18-2019, 10:38 AM
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fan in front runs off sensor only.....I ran a grounded switch in the dash and ran the green/black wire going to the fan to it so I can turn it on whenever....although, I'm in S fl and really don't see any difference in engine temps when I use it....I think it's pretty worthless for cooling anything....I have an 85
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