I've seen e-bay listings for temp sensors that actuate the aux fan at a lower temp. Has anyone purchased one of these?...do they work?...advisable?

Item 110186994155

Thanks, Matt

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Birmingham, AL
2006 Audi A4 "Audrey"-daily driver
1976 MB 450SL "Marlene"
2000 Jetta VR6 "Julia"-traded at 220k miles
1997 Jetta 2.0Trek "Blanche"-traded at 450k miles YES 450,000 miles
1986 Prelude "Gladys"-died at 120K miles