2005 impala 3.4L over heating. Coolant fan only comes on if A/c is on.

Asked by Liccketto Dec 03, 2017 at 11:03 PM about the 2005 Chevrolet Impala FWD

Question type: Maintenance & Repair

I have a 2005 impala 3.4L. It over heats and only way to
keep temp down is to run a/c so that the coolant fan will
stay on, otherwise it never comes on. I have replaced
radiator, thermostat, temperature coolant sensor and all
fan relays with no luck. Any suggestions would be greatly
appreciated.

1 Answer

635

After everything you replaced it sounds like the ecm is not reading the coolant temp sensor.When it reaches a certain temp the ecm sends voltage to the fan relay.When in ac mode,the ac circuit sends the voltage to the fan relay direct,bypassing the coolant temp sensor .

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