A trivial question...

As per the title - when C/Control is on auto, I know it adjusts the fan speed in an effort to reach the desired (set) temperature inside the cabin by increasing the flow of cooled air, but I suspect that the compressor is always engaged.  Or will the compressor eventually cut out, once the fan speed has been running on minimum for a while, perhaps.?? The air coming through always seems to be cooled whenever I have "AC ON" displayed.

Do any of you experts know?

Many thanks.

Modern AC compressors are variable.  No longer simply switched on or off.  (Plenty of YouTube vids showing the internal operation if you're interested.)

However, with the CC on Auto in the Mk3, the AC is always switched on to 'condition' the air, rather than just cool it.  There will of course be a cooling effect from that process, even if heating at the time.  You can switch the AC off manually if desired.

The Auto mode doesn't just alter fan speed.  It also adjusts the direction of air using the sun load sensor and the temp sensors located around the vehicle to determine where more or less cooling is required.  This happens even when in single mode, although obviously more noticeable in dual zone mode.  The other function that Auto includes is not blowing cold air straight into your face on a cold day, it keeps vents pointed at the windscreen until the air is warm enough to direct to the occupants (either from coolant warm up or from an auxiliary heater, depending on engine type).

Thanks for that explanation, Tom.

It all makes sense.