Volkswagen Repair: one fan works ,one does not, coolant temp, temp gauge

Question
i have 2001 jetta gls 2.0 i just replaced the coolant temp sensor.now today i noticed that only the small cooling fan is running.and that my temp gauge is still running at 190.should the bigger fan be running also,or when does it run,and how and what do i check,please explain how the fans work what to turn,what setting to make work,this is my first vw and do like it.thanks for your help.preacher in okc with vw trouble.steve miller

Answer
Steve, thank you for your question.  There are three different temp sensors.  One for 160, one for 190, and one for 210.  I have seen other temps listed in the past for temp sensors. If only one fan is coming on, that is usually a messed up sensor.  I have gone through 3 or 4 before getting a good one.  Both fans will kick in when the temp is above the limit of what the sensor is reading, example: once the temp goes above 180 then both fan start and run until the sensor reads the temp of 180.  If you had a shop to the work, they might have not connected the big fan back to power.  You should see an electric line coming from the big fan.  It is possible it is not connected or the line is damaged.
Hope that helps