I had read through 1999 Ford Escort Owner’s Manual, and have few questions regarding air conditioning modes. The manual’s section on climate control states:
The air conditioning compressor will operate in all modes except [floor] and [panel]. However, the air conditioning will only function if the outside temperature is about 10°C (50°F) or higher.
Is it normal that A/C is engaged in most climate control modes outside of clearly marked [A/C], and [Max A/C]? Is it model-specific feature, Ford deal, or many manufacturers A/C units work the same way?
From maintenance standpoint (wear and tear of the A/C system, extra load on the engine etc.) does simply engaging the compressor and “functioning A/C” differ much, if at all?
Similarly, how big is the difference between [A/C] and [Max A/C] modes? Somewhat counter-intuitively, [Max A/C] is more economical (it is obvious once you know that it is the only mode that recirculates interior cool air, it is just not obvious to know that), but how much more?
I understand the idea behind using A/C in [Defrost] mode (A/C removes considerably moisture from the air, thus it is used to prevent fogging of a windscreen), but why is A/C used in combined [Floor and Panel] mode? Especially, since individually [Floor] and [Panel] are A/C-free, as mentioned above?