Sure enough. After 23 years of owning my 124 and studying its systems thoroughly, I learned something new today. Looks like an easy diagnostic test for it too. Still trying to figure out why the CCU needs to monitor outside temp in order to keep inside temp at a set level. Anyway, thanks for the info.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't