How does A/C work?

[Alex]

In terms of CAN signals. Did MB ever publish this information? Trying to find out what controls the swashplate angle in the compressor.

Long shot but you don't ask, you don't get.

 

[Diesel Benz]

Front SAM likely. Which car are you talking about?

 

[Alex]

The a/c has only one wire going into it and that's from the engine ECU. I want to find out what exactly is being transmitted so I could replicate the behaviour. The car is 2003 211.

 

[Diesel Benz]

Sure? Which car are you talking about (exactly, please give us the VIN)? What is the part number of your engine ECU?

 

[Alex]

Positive. The car is 2003 E55. A1131533979 is the ECU p/n.

 

[Diesel Benz]

Positive. The car is 2003 E55. A1131533979 is the ECU p/n.

Looks like your car is unique. This is how other W/S211 E55 AMG cars are built:

 

[Alex]

My CL55 is unique too then. Both are early production cars and have identical single wire connection to the a/c.

 

[Diesel Benz]

My CL55 is unique too then. Both are early production cars and have identical single wire connection to the a/c.

Single wire yes but on other cars this single wire goes to the front SAM, not to the engine ECU.

Not a big deal though, all these control units share information and are aware of the AC compressor state etc.

 

[Vitobrabus]

In variable displacement compressors it's normally mechanical. As the suction pressure rises, so does the angle of the plate....this them pumps more refrigerant and lowers the suction pressure until it balances out.