Hi, unfortunately on the W211 model Mercedes like yours there is no way to erase the fault codes in the climate control module without the use of a Mercedes scan tool. You do not necessarily need to get this done at a Mercedes dealer. Most independent Mercedes repair shops are able to erase the fault codes. I would charge 1/2 hour labor to connect to the car and erase the fault codes. This would not include any testing or diagnosis of the a/c system. Click here for the Bosch Car Service Center locater. Enter your information and you may be able to locate a shop in your area. I know that this is not the answer you were hoping for but this is unfortunately the only solution. Let me know if you have any questions.

It does not need to be the factory tool but it must support the Mercedes systems. As long as it supports Mercedes it will work.

Most generic scan tools only read the engine control module.

It must be able to go deeper into the vehicle systems and erase codes in the climate control module.

Correct, a generic scan tool will not be able to scan the climate control module. It also will not be able to scan many of the other computers in the car.

There are many aftermarket scan tools that support Mercedes and most all of the independent Mercedes repair shops have a diagnostic tool that can read and erase codes in the climate control module but a general repair shop will most likely not have the capability.

Some of the major parts chains carry factory level scan tools but the cost is in the thousands.

Autel probably makes the most affordable factory level tool on the market now.

You're quite welcome