Climate Control unit is possessed - no codes
 

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??

Have you replaced or done something with your radio in recently? There is a little tube back under dash that often gets broken.

I changed my radio several years ago, but have had the problem for a long while (just lived with it). What is this little black tube?

Did you try to reset your CC?
I believe this is for your model:
With the key in the ignition and in posistion 2 push both the defrost button and the recirc button (at the same time) for five seconds or untill the led lights in those buttons begin to flash. Wait for 30 seconds or untill the led's stop flashing. Switch off the ignition.

and what does that little black tube does, where do I locate it and check it out? Thanks!