Larry,

How true. So many people have this idea that if they turn a thermostat to its extreme setting the temperature will change faster. They don't seem to appreciate that in a closed loop system with feedback the heating or cooling is either on or off as required until the desired temperature is reached.

I think I finally have convinced my wife to leave the temperature controls alone in our 300TE but I still see my father setting those in his E320 coupe at extremes. Unlike the fully automatic system you got in the US, most W124s in Australia got the (very reliable) manual climate control system which still was a closed loop system (except with separate left and right temperature zones and manual fan speed and air direction controls). I even submitted an article to our MB club magazine explaining to owners how the sytem should be used after noticing that most owners constantly fiddled with the temperature controls and often set them to extremes. Even the owner's manual recommends 22 degrees C as a comfortable year round setting.

As to the topic of this thread, we usually leave the aircon enabled year round (the EC economy button disables it) since the compressor will only engage should the cabin temperature require it anyway.

Attached image shows the system most of our W124s got (note dual temp controls calibrated in degrees C).

Attached Thumbnails

 

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.