Winter and Heater (A/C)

[Snappy]

In the US, the All Weather Pkg cars have the ceramic auxilliary PTC (Positive Temperature Cooeficient) heater. When does it kick in?

From the AC section of the manual:

"When the PTC heater operating conditions are met
(engine at idling speed or faster, ambient temperature is
10°C (50°F) or less, engine coolant temperature is 65°C
(149°F) or less, and No. 3 heater control knob setting is
MAX HOT), turn the blower switch to the Lo setting."

Does my car have one? Look at the _AC_ _Amplifier_, a black box screwed under the main AC box behind the center console. (Put your head down by the pedals, look under the left side of the center console, pushing the carpet out of the way.) TWO connectors? You have the PTC heater. One? No you don't. All this info applies to 2007 spec US models, others I don't know.
See selected pix from the online manual.
(Sorry if it is clear as mud.)