Here's a good article on the ETR on a R107, with a great explanation on how it works. Mercedes-Benz R107 A/C Temperature Sensor ETR Switch Replacement | 1972-1986 - 450SL, 380SL, 500SL, 560SL | Pelican Parts DIY Maintenance Article

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked