Well, something is not right. A/C should be pretty cold and air flow should be fairly strong. Louder than a '99 E320 or an S class? Yes, definitely louder.

One thing you can do is turn the temperature wheel all the way to max cold.
You should end up with very cold air. Also pressing the air recirculation button on the climate control panel. This should improve cooling by eliminating outside air.

Sounds like you are having transmission issues. At that mileage you might want to have someone check the shifter bushings. On my '92 the mechanic told me they had essentially rotted away to nothing. Also transmission fluid and filter every 30,000 miles.

I am certainly no expert. I have had A/C problems on two different W124's.
Both times it was compressor failure.

Steve