Hi Guys. Really need your help here. My ac had a leak which I fixed
I put a new receiver drier and vaccumed the system down before attempting to recharge. The faults were cleared with icarsoft mb2. AC compressor was changed 2 years ago. Compressor won't engage. AC light is on, but nothing happening. No further faults have appeared. There is enough refrigerant in system. Please help. Coukd it be a fuse or relay

 

The AC compressor on SL350 is a clutchless type, and so is always engaged. There is no clutch!

It is a variable output compressor, and its output is controlled by the Front SAM in the form of a PWM (Pulse Width Modulation) signal. You need an oscilloscope to check it.

However with a 12Vdc signal it will be controlled to 100% output.

Also be aware that the AC light is ON when the AC is OFF!!!! (though depending on age it might be ON when AC is ON, depending on who was in charg of Mercedes Software at the time!!!)

You should be able to check the pressures of the AC system, and the valve actuations with your iCarsoftMBII, but you would be much better with a full Star/DAS system.

Make sure the low pressure fault is cleared after re-gassing, as the system will not run untill the old fault is cleared.

 

Reiterating this portion in particular:


When the system is recharged with refrigerant after depletion, it MUST be reset by clearing the low pressure fault code.