My experience with the heating / ventinating / a/c systems is limited. What I know I know well, but I've not learned or worked on a wide variety of systems.

But I have wondered for years -

In my 240s, 1977 through 1988, the heater valve varied the flow of hot engine coolant through the heater core. The a/c switch has a knob that makes the compressor run more frequently or less. Thus between the two I have control of the general comfort level.

Many times on longer road trips we set the controls to have a wee bit of heat and a wee bit of a/c so that the cabin air became pleasantly warm (or cool) and very dry.

Now comes my 1997 965. All I see is the three knobs. Fan speed, air direction, temp setting. Two on/off buttons: Inside air or not, and a/c or not.

My old 1969 Ford Galaxie 500 (the one with the 2-inch gas line and pump at both ends) used a pretty simple system. A/C on (with a switch) all the time with an internal control to avoid freeze-up. Heater on all the time. Cabin air temp was controlled by changing the blend of heated or chilled air through an air plenum.

What does the 960 do? Blend air or ??? When the a/c button is in (a/c on) the frequency of compressor kick-in seems independent of the temp setting.

Just curious, guys and gals.


Thanks,

Bob

:>)