| Soyuz008 |
10-04-2013 08:33 PM |
Re: A/C and Entropy Fans
In most modern OEM dual fan systems, low speed is when both motors are wired in series with the battery (approx 1/2 battery voltage to each motor). High speed is both fans are wired parallel with battery (full battery voltage to each motor). It is pretty rare to run one fan only for low speed (it is still done on some vehicles...many JOEM...but not often). One fan only operation, pulls hot air from the engine (through the non-running fan opening) and re-circulates it through the radiator. In most instances, this actually makes the coolant increase in temp.
In modern OEM fan systems, the fans are not turned on simple because AC is on. They are operated by AC head pressure (plus other inputs) and may cycle off to low or low to high depending on AC needs or cooling needs.
Fans are not turned off above a set vehicle speed. If the various cooling needs are met, the fans turn off, if anything is still above the shut off limit, the fans will run no matter how fast the vehicle is travelling.
The above is not based on internet myth. I have been supplying OEM coolings fans to GM, Ford, Chrysler and BWM for many years. I have spent hundreds of hours in the climatic wind tunnels tuning and calibrating electric cooling fans for cars and trucks.
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