[wwest]

Serious, honest, question.

Several owners are saying sub-freezing vent temperatures are not only possible, but desirable.

I am well aware that lots of BTUs are required for water to change state from liquid to a solid, ice. and that takes time even with the evaporator core well below freezing.

These are owners seemingly in the HOT and HUMID mid/deep south.

I have had instances of evaporator freeze up in several Lexus LS vehicles, 2 '92's and a '95, both happening on a climb to an elevated altitude, at a 2000-3000 foot level. Obviously some climatic anomaly with the Lexus system since the evaporator core remains LOCKED (verified in at least one instance) at 33dF.

So my question is: how is it possible for an air-cooled 911 A/C evaporator to NOT freeze up during a longish drive with >50% Rh, and the vent temperatures well below freezing, therefore the evaporator core even moreso.

An additional question: The T-stat on/off range/span/hysteresis is supposedly 26dF +/- 2dF, to 33dF +/-2dF. Obviously the average being below freezing. Again, how does, how can, this work absent evaporator freeze-up?

Note: I have read about numerous instances of owners reaching sub-freezing vent temperatures via lifting the capillary tube sensor partway out of the evaporator core, only to later discover that led to freeze up.

Conundrum?