The side front windows on my 2014 Toyota Highlander fog up in the humidity
Your Highlander Limited Platinum has heated mirrors. Do you have the owners manual? You say windows and mirrors...both?
http://www.toyota.com/t3Portal/document/om/OM48A12U/pdf/sec_06-01.pdf download that and see page 424 - 426, it shows how to defrost/defog both
The problem is that the defogger draws air from the outside, which may have contacted either the engine or the hot exhaust. Turn on the recirculation, turn on the a/c, turn off the defogger, set the temperature to 74. The air in the vehicle will dry out actually clearing the windows from the top to the bottom.
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