Thanks for the feedbacks. I managed to get another mechanic to look at it today. Attached, please find a new code that he managed to pull from his scanner.
This is the 3rd mechanic that has charged me but at least his scanner showed something different from before. What is your view based on the new code?

 

Can you actually read the code number ??? No it’s unreadable. But it says fan short to ground! Check the connections for corrosion if not better replace . I wonder if spraying it inside with electronics cleaner would be worth it? It would be worth getting one ordered today and shipped . FCP euro stands behind their lifetime warranty

 

Codes are readable for me (the only challenge is the image was posted 90* clockwise)
.
.
0521: Charge Movement Flap Malfunction: (Common on E350, GLK350, ...) A broken pivot arm, carbon buildup, or faulty actuator in the intake manifold flap system, affecting airflow and causing RPM issues.
.
0694: Points to an issue with the electric cooling fan 1 control circuit, usually a "high" signal, meaning the PCM/ECU sees too much voltage, often causing the fan to run constantly or erratically, leading to potential overheating and A/C issues, and usually involves a ... bad fan relay, wiring short, or faulty sensor.

Common Symptoms:
Cooling fans run at high speed constantly, even with the engine off.
Engine overheats.
Air conditioning may not work.
Temperature gauge fluctuates.

Common Causes:
Wiring Issues: Shorted wires, corroded connectors, or open circuits in the fan 1 circuit.
Faulty Fan Relay: The relay controlling Fan 1.
Bad Fan Motor: The electric fan itself.
Faulty Coolant Temperature Sensor (CTS): Inaccurate readings.
Damaged Control Module: ECU or PCM.


If you don't have the proper tools to pin-point the issue(s), take it to a capable MB mechanic.

 

Thanks. Yes, these are also what I gathered through AI.
The mechanic confirmed that I need to change the fan.
At this point, I am hoping to get feedback from those that faced the exact same issue to conclude my next step.

 

Look into a Carly scan tool for 100$ , or some other scanner ! for the future ! I think you will be ok fixing the fan. A scan tool would have saved you $$$$ .

 

Agree completely. And for reference, it looks like your mechanic is using a Launch CReader, which is available on Amazon for less than $150. Even if you don’t do the repairs yourself, you go in with a good idea of where the problem is.

 

Read what Calder Cay said and follow his advise , it could be a simple cheap relay , or temp sensor , and not the fan . It still needs diagnosing

 

This may sound rude, but I can’t believe I’ve read all this nonsense and there’s no report of checking the coolant in the morning. There is a statement that parts had been replaced that opened up the coolant circuit and could leave an air bubble in there. We’ve heard nothing about re-vacuuming the system or have seen a picture of the coolant after it is completely cool in the morning. Forgive me if I’ve missed it, but I reread the entire thread and kept checking back in before I wrote this. I personally find it very hard to offer anybody any help that doesn’t start at diagnostic step number one and doesn’t listen to suggestions.

Now you have a code that points to a fan having been burned up…. What burned up the fan?… I know exactly what caused my fans to be effected last time a mechanic touched something that effected them.

good luck and don’t burn up your new parts.

 

he said he has checked the fluid when cold it’s always full, with my Glk I didn’t need to Vacuum the system , after about 5 minutes driving i just refilled it as the air went out the system . Calder cay read the code and said a relay or temp sensor could be one of the several causes, how about a corroded connection, that could cause it. the fan is most likely, but 10$ fixes are still possible. Fans aint cheap , but I am ! How does someone burn up their fans? Checking the relay is diy, it could be something controlling the fan like the sensor or a corroded connection, it is a 16 year old!

 

The OP, for these purposes, also wrote this in post #16, which seems to possibly be a suspect observation:


"The coolant has fresh antifreeze, and it is on the max level when cool or hot."


"cool" and "hot" can have different meanings to different people but it's a bit odd the coolant level would be seen "on the max level" under both circumstances.

 

Hot it’s at 12-15 lb? I would think he waits until it cools and pressure is released ,

 

sounds reasonable but it has nothing to do with point I'm trying to make - coolant LEVEL at the two different temperatures