We used to own a 2004 Ford Taurus, and I noticed n winter the tranny would not hit OD as earlier as the summer. I only had a 5 mile commute to work. I learned the tranny has a temp sensor that prevents the converter from locking when the fluid is too cool. So, in the winter I used a little space heater on a timer, pointed at the tranny It would run for about an hour, just prior to me leaving for work. Warmed things up enough to lock the convert just like summer.
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