Please see the attached image to demonstrate the warning I am receiving. This is all that comes up and then usually goes away and comes back on every 30 seconds to a minute. Some drives it doesn't come up at all and others, it comes up the whole drive. The car does not overheat but when the light comes on my AC stops blowing cold. It's still on just no longer cold. I turn the AC off and the light usually goes away. It is an intermittent problem and sometimes it comes on almost constantly while driving and other times it won't come on for a day or two of driving. My coolant level is fine, I've burped the system and no bubles come through anymore. Car is a 2007 CLS 550 w219 with 217k miles.

Things I've already done:
Changed radiator, thermostat twice, coolant temp sensor, and coolant reservoir as well as coolant.

I have burped the system several times and turned the heat on full blast, jacked up the front of the car and opened the line to the heater core which helped burp the system and brought the heat back to the AC.



My thoughts are it still may have a bubble in the cooling system but I've done everything I can find to get them out without luck.

The problem started when I had a coolant leak in the radiator and the level got low and this light would come on and so I would add coolant and the light would go away. Then I decided to change the radiator and thermostat (since it was failed open and needed changed) the light would still come on randomly. I then changed the thermostat a second time as well as the coolant temp sensor at the back of the block which did not fix the issue either.

I burped it again after the thermostat and the issue persists and the coolant level is full and shows no signs of bubbling any further after running without the cap for 15+ minutes.

I am at a loss and need help, what else could it be? I have had it connected to STAR and there are no codes related to the drivetrain or coolant system.

 

An additional detail that may help, when I turn the AC off the light tends to go away and stay away until I turn the AC back on then this light comes on. Not always but usually, not sure if they are related or not.

Also when this light comes on my coolant temp will usually raise or lower by a few bars. Never gets above 90 and sometimes has this light on within the first two minutes of driving before its even warmed up so I know its not actually over heating.