When really hot outside, the climate control unit on my 97 E420 flickers on and off (recirc light blinks on) untill the car cools down. Sometimes the probem continues even when cooled down. The climate control unit will not flicker if I disconnect the instrument cluster and, most times, will stop flickering for a while after I reconnected the instrument cluster.

I have not codes stored in my climate control unit (except of course after I disconnect the cluster, which I then clear). I have replaced the outside temp sensor and engine coolant temp sensor for good measure (since they are linked to both the inst cluster and the climate control). I am at a complete loss.

Any ideas??

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