You definately need to fix it.
This is how the climate control monitors temp inside the car. If it is not working, the climate control will be slow to react and temp control will not be accurate.
Brian

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Mercedes Benz Master Tech
ASE Master Technician
Diagnostic Technician
Owner of "Behind the Star Inc."
Raleigh NC.
www.behindthestar.com
brian@behindthestar.com