Like A264172 said, it is good to 'exercise' the system once in a while during the cold weather months to keep parts properly lubed and sealed. I think modern MBs are designed to kick in the a/c once in a while, such as during startup. Using defrost will definitely activate the a/c. Beyond that, there is no other maintenance that can be done to your system. You pretty much leave it alone and only service it when anything goes wrong.

Dave, your friend is correct about leaving the system alone and avoiding any mechanical intrusion.

The reason your system cycled off during full throttle condition is because of belt slippage. The system senses when the belt slips on the a/c compressor so it can shut down the compressor in cases where the compressor starts siezing in order to prevent loss of the serpentine belt. Losing the belt would leave your car dead on the side of the road. The a/c system will reset next time you start the car. You should take this clue and consider you may need a new belt, a new tensioner, or both.

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95 E320 Cabriolet, 169K