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Old 03-09-2021, 11:46 AM   #4 (permalink)
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Originally Posted by Piotrsko View Post
My understanding is the fans are driven on by a temperature sensor somewhere in or near the peak temperature spot in the cooling system. Ditto for multi-speed. When you have the A/C on you are dumping hot air into the cooling systems input effectively making it a very hot summer day. My golf reduces engine power if it gets too hot after measuring intake temps. If you think there's a benefit to killing the fan, just disconnect one at the fanhousing power connector and measure the change. Those connections are made to come apart.

On the other hand the F250 fan mostly idles,BUT it has 8 gallons of coolant and is overcooled for most operations below 1/2 throttle
Thanks. On my car the fans are activated by a temp sensor in the engine block when the coolant reaches 207 degrees or whenever the AC compressor is engaged regardless of coolant temp or speed to cool off the condenser. Problem is that the fans don't need to be running while driving down the highway as there is already plenty of natural airflow to cool the radiator and condenser.
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