What happens: From time to time, the control unit recirc light will blink and the display reset itself to the value when the car was first turned on. When that happens, the blower motor turn off for a few seconds and then comes back on.

What I tested: there are no codes stors in the unit associated with this malfunction. If I unplug the instrument cluster, the probem goes away and the system with not "blink". When I reconnect it, the problem often goes away for a few hours or a few days.

Any advice on where to turn? I do not think it is the control unit itself since it never has that problem with the instrument cluster disconnected. It is also really strange that I do not get any codes.

Very, very frustrating.

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2008 S550
2010 GLK350
1997 E420 (retired)
2005 CLK500 (retired)