There are several cabin temperature control systems fitted to the various models.
What is "Climate Control" (on a P reg, 1996 XM TD 2.5) as opposed to Air Conditioning?
There were several 'climate control' systems fitted to the XM. In fact, IIRC the manual refers to them all as 'climate control'. Onseries 1 there was:
2) Semi-auto (looks very similar to manual)
3) Full auto
1.5) Later series 1 also came with manual but separate for driver and passenger side.
This was carried over to series 2 (but looks different due to different dashboard design). I am not sure about separate left/right, though.
The 2) and 3) normally came with the AC. It is possible that in other markets one could get AC without the semi or full auto, but I have never seen one, except if it was an after-market job. Also, the only non-AC semi or full aoutos were the ones that had a non working AC or (in some cases) it was actually removed, probably after a failure that was deemed to costly to fix.
The difference from manual/semi-auto is that the temperature 'dial' is marked in C (on series one from 14C to 28 I think). The manual jjust has blue and red stripes. Full auto looks completely different, all controls are electronic (semi auto has manual direction and recirculation control just liuke fully manual) and are buttons, not dials, and there is a temperature display on it. In most of continental Europe this version only came in Exclusive models. Both auto and semi-auto have control of temperature via several probes (one is behind a small fan beside the dome light, others in the ducts).
I had the semi-auto on my car and liked it - that is, once the black interior would cool down after being heated by the sun through the glass :-). The system also varies fan speed depending on a simple set of rules operating on the temperature set on the dial, the actual cabin temperature, and the outside temperature. It works even if the AC is stopped, attempting to come as close to the setting on the dial as possible. If there is a big difference between the set and the actual temperature, the fan speed will be higher - in fact it can actually go to full speed too. If you left the car in sunlight, it would reward you with a blast of air once it was turned back on again, in an attempt to cool off the interior that has heated up a lot. Even with these small quirks I found it doing a good job and littel adjustments were ever needed - I liked to keep the temp at 22-24 depending on season and let it to it's job. The semi-auto does not know that you may have put the system to recirculation or to blow in a certain direction which may not be entirely consistent with it's chosen fan speed. Full auto includes information about direction and recirculation settings in it's rules, it has a couple of semi-useful presets, like defog etc. I considered converting from semi auto to full auto for a time but in the end decided against it after having a long trip in a V6 exclusive equipped with it. The system works perfectly fine but it wasn't THAT much better than what I already had in the car.